Monday June 2nd 2025 |
8:30-9:25 AM | Transportation And Registration |
9:25-11:00 AM | Session 0 | Chair: Emily Griffith |
9:25 AM | SOC and LOC Conference Welcome | Emily Griffith & Jaime Villaseñor |
9:30 AM | Welcome | Juna Kollmeier |
9:45 AM | COINS: The Committee on Inclusiveness in SDSS | Emily Griffith |
10:00 AM | Survey 101 | Keith Hawkins |
10:30 AM | Let's Bring your SDSS Research to a Wider Audience | Niall Deacon |
SDSS is a collaboration of hundreds of scientists and I would like to get you involved in two overlapping areas: education and public outreach. SDSS has a great track record of producing educational activities using real astronomical data, from Plates for Education to Voyages to Python notebook for first year university students. We’d like to expand these activities to include current SDSS research topics and to this end developed introductory university level notebooks based on Milky Way Mapper and Black Hole Mapper themes that will be released with the upcoming data release. But we want to do more and you could help us design activities around your science. We also would like to bring your science to the broader public. This could be through SDSS astronomers giving public talks or featuring your work on SDSS’s social media or press releases. So I’d like to hear from you, what should the world know about your science? What’s the one thing about your science you wish that a person you walked past in the street knew? |
10:45 AM | SDSS-V FAST: Updates & International Opportunities | Dhanesh Krishnarao (DK) |
The Faculty and Student Teams (FAST) program has recently begun its fourth iteration, FAST 4ward, with support from the National Science Foundation to provide increased funding and student support to Minority Serving Institutions in the US. Here, I will share updates on the program overall, existing opportunities to expand the impact of FAST to our international members and community, and will seek feedback and new ideas to broaden the impact of FAST and SDSS beyond the US. |
11:00-11:30 AM | Coffee |
11:30-12:30 PM | Session 1 | Chair: Emily Griffith |
11:30 AM | SDSS Data Access 101 | Anne-Marie Weijmans |
TBD |
12:00 PM | Milky Way Mapper Overview | Andrew Tkachenko |
Milky Way Mapper (MWM) is one of the three overarching science programs in SDSS-V. The MWM Survey employs BOSS low-resolution (R=2000) optical and APOGEE high-resolution (R=22500) near-IR instruments to reach its ultimate goals. The MWM Survey is primarily concerned with understanding the dominant formation mechanisms of the Milky Way and its place in a cosmological context. In this talk, we will provide an overview of the current status of the MWM Survey and will highlight some of the most exciting future prospects. |
12:30-1:30 PM | Lunch | |
1:30-2:00 PM | Speed Geeking | Outdoors |
2:00-3:30 PM | Session 2 | Chair: J. Villaseñor |
2:00 PM | Local Volume Mapper Overview | Niv Drovy |
We will give an update on the Local Volume Mapper project. We will give an overview of the project, address survey operations and progress, discuss the state of the data reduction and analysis, and highlight science results. |
2:30 PM | Black Hole Mapper Overview | Amy Rankine |
Over the course of SDSS-V, Black Hole Mapper (BHM) is collecting spectra of ~300,000 active galactic nuclei (AGN) across a range of programmes. Via follow-up of eROSITA detections, BHM is focusing on objects expected to be AGNs based on their X-ray emission in order to explore AGN demographics and evolution. Additionally, through repeat observations of AGN in the AQMES programme, BHM is time-resolving the inner regions of the AGN and changes therein to better describe the physics and dynamics that drive these fantastic phenomena. With even greater time resolution in the RM programme, black hole masses can be measured accurately and scaling relations for the wider population refined. I will provide an overview of BHM and its progress thus far, as well as document some of the scientific projects led by members of the SDSS-V. |
3:00 PM | eROSITA Overview | Johannes Buchner |
After introducing the principles of the X-ray imaging-spectroscopy telescope eROSITA on board of SRG, I will discuss properties of eROSITA's first all-sky survey. The survey scanning pattern and the flux limit have implications for the detected astrophysical populations and their X-ray data. The data available through the eROSITA-SDSS collaboration and how to access it will be introduced, as well as approaches for timing analyses and modelling of X-ray spectra. I will end with science highlights from eROSITA extragalactic astronomy, with a focus on active galactic nuclei. |
3:30-4:00 PM | Coffee |
4:00-5:20 PM | Session 3 | Chair: Mara Salvato |
4:00 PM | eROSITA 101: Galactic science with eROSITA | Axel Schwope |
eROSITA has performed four complete X-ray all-sky surveys in the energy range between 0.2 and 2.3 keV. With its large field of view (>1 deg), and its much improved spatial and spectral resolution compared to its predecessor ROSAT it is the instrument to unveil the sources of high-energy emission from our own Milky Way at unprecedented sensitivity. I will describe the strong synergies between LVM/eROSITA for studies of the diffuse emission and BOSS/eROSITA for studies of the point-source emitters. X-ray point sources fall in two broad categories, coronal emitters and accreting compact objects. While eROSITA is the machine to detect the interesting sources, optical follow-up is needed for classification and sample composition. The joint study allows to build comprehensive samples of all kinds of X-ray emitters. |
4:30 PM | New Period-Bounce Candidates Among eROSITA-Selected Gaia White Dwarfs | Daniela Muñoz Giraldo |
Period-bounce cataclysmic variables (CVs) are systems in which a white dwarf accretes from a brown dwarf donor, having reached a point where the degeneracy of the donor reverses the orbit period evolution. A large portion of the CV population, between 40% and 70%, is predicted to be made up of period-bouncers. However, only a few of these systems have been confidently identified so far. A promising approach to identify period-bounce CVs is an X-ray detection. It provides proof of accretion from the substellar companion onto the white dwarf because the coronal emission of a brown dwarf donor is below the sensitivity of current instruments. Based on the known multiwavelength properties of period-bouncers, we have constructed a ”scorecard” that assigns to a system its probability of being a period-bouncer. Additionally, confirmed period-bouncers detected by the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) onboard the Spektrum-Roentgen-Gamma spacecraft (SRG) are used to establish X-ray selection cuts that reflect the typical X-ray emission of period-bouncers. Applying both the scorecard and X-ray selection cuts to our catalog of known CVs around the period-bounce, introduced in Muñoz-Giraldo et al. (2024), resulted in the confirmation of 12 new period-bouncers, a promising 63% increase in their population. However, the search for the missing population of period-bouncers continues. Considering that the contribution from the substellar companion in period-bouncers at optical wavelengths is expected to be negligible, the next step is to search for new candidates among Gaia white dwarf catalogs using the same scorecard and X-ray selection cuts applied to our catalog of known CVs around the period-bounce. Using this method we have identified 153 strong new candidates. We provide an outlook of the capabilities of SDSS-V for the confirmation of these strong period-bounce candidates. |
4:42 PM | The Hot Phase of the Interstellar Medium | Manami Sasaki |
The interstellar medium (ISM) is heated and ionized by radiation, by stellar winds, and finally, by supernova explosions. Since these processes are often correlated in space and time, the combination of stellar winds and supernova remnants (SNRs) can form large interstellar structures called superbubbles, which are filled with hot thin plasma. If superbubbles expand and break, the hot plasma will escape into the galactic disk and also out of the disk, forming galactic winds and fountains. The hot plasma in SNRs and superbubbles can be studied best in X-rays due to its high temperature (10^6 − 10^7 K), while particles are also accelerated in the shock waves. We will present recent results of studies of the hot phase of the ISM in the Milky Way and the Magellanic Clouds carried out with eROSITA and discuss the physics of the hot plasma, the evolution and energetics of SNRs and superbubbles, and the implications for the star formation history of galaxies. |
4:54 AM | X-raying the Multi-Phase Interstellar Medium of the LMC with eROSITA | Martin Mayer |
A large fraction of the interstellar volume of most galaxies is occupied by million-degree hot ionized gas, energized primarily by supernovae and stellar winds. While tenuous, this phase provides significant pressure compared to colder phases of the interstellar medium (ISM), and is crucial for driving outflows and star formation. X-ray observations provide a unique window into the characteristic thermal emission of this hot diffuse plasma, particularly in nearby galaxies where its distribution can be effectively mapped, the prime example being the Large Magellanic Cloud (LMC). Given its location close to the survey pole, the LMC was observed with exceptionally deep coverage in the SRG/eROSITA All-Sky Survey (eRASS), offering an unprecedented view of its hot ISM phase, and complementing existing observations tracing cooler gas components. In this contribution, we will present the results of a morphological and spectroscopic analysis campaign of the ISM in the LMC, based on the full available eRASS, complemented with HI, infrared, and optical data. We show that diffuse hot gas with typical temperatures of 3*10^6 K and pressures of 10^4 to 10^5 K/cm^3 permeates the majority of the LMC. In particular, we are able to quantitatively demonstrate a strong anticorrelation between the distribution of hot and cold ISM phases, on characteristic scales of 100 to 1000 pc. We compare the ISM pressure to quantitative predictions of energy input from reconstructed star formation histories, and identify regions of excess pressure, arguing for additional sources of heating. Finally, we find a large-scale gradient in alpha-element (O, Ne, Mg) enrichment of the ISM, providing new constraints on the contribution of massive-star nucleosynthesis to the ISM metal content. |
5:06 PM | The SDSS Legacy Archive at MAST: A New Access Point for SDSS data | Julie Imig & Brian Cherinka |
The SDSS Legacy Archive at MAST (SLAM; http://archive.stsci.edu/sdss) is a new resource to access copies of all science-ready SDSS data hosted at the Mikulski Archive for Space Telescopes (MAST). Through SLAM, SDSS data is now available through the same interfaces as HST, JWST, TESS, Pan-STARRS, and Gaia data, opening up new opportunities for scientific synergies between missions. Currently, data from DR17 APOGEE, MaNGA, and eBOSS are available in SLAM, with plans to expand to more surveys in the near future, including SDSS-V mappers. In this talk, we will present the current status, introduce different access points and tutorials for using the SLAM, and solicit feedback from the community to help guide future development work. |
5:20 PM | Transportation |
Tuesday June 3rd 2025 |
8:30-9:00 AM | Transportation and Coffee |
9:00-10:30 AM | Session 4 | Chair: Zheng Zheng |
9:00 AM | LVM 101: How We Can Study the ISM with LVM | Kathryn Kreckel |
Connecting studies across the pc (sub-GMC) and kpc (galaxy-wide) scales is fundamental to understanding the physics governing star formation, the structure and energetics of the ISM, the baryon cycle, and ultimately, the evolution of galaxies. The Local Volume Mapper (LVM) in SDSS-V is taking the first step towards the “spectral panopticon”, a full spectroscopic image of the sky, and covers the bulk of the southern MW disk at 0.1-1 pc resolution and the entire Magellanic Clouds at 10 pc resolution. It provides optical IFU data to resolve ionized gas structures, including HII regions, planetary nebulae, supernova remnants, and diffuse ionized gas. This provides a rich counterpart to the existing multi-wavelength studies of the dense gas and individual stars within these systems. Scientifically, LVM will resolve the regions where energy, momentum, and chemical elements are injected into the ISM at the scale of gas clouds, while simultaneously charting where energy is being dissipated (via cooling, shocks, turbulence, bulk flows, etc.) to global scales. This talk introduces the core science goals of the LVM, and presents some initial results on global vs resolved views of the Orion Nebula. |
9:30 AM | Unveiling the Orion Nebula: A Comprehensive View with the Local Volume Mapper | J. Eduardo Méndez Delgado |
The Orion Nebula is an extraordinary laboratory for studying the internal physics of ionized nebulae. Its proximity (0.4 kpc), high surface brightness and unique geometry as a blister open towards the Earth's line of sight make it an ideal target. This region has been extensively studied due to its optimal characteristics, revealing complex internal structures such as Herbig-Haro objects, photoionized protoplanetary disks, and intricate filamentary features. However, previous investigations have primarily focused on the dense and highly ionized Huygens region, leaving the rest of the nebula fragmented and underexplored. For the first time, the Local Volume Mapper (LVM) enables a homogeneous and comprehensive study of the entire Orion Nebula. Using seven dedicated pointings, we have mapped the entire ionized gas structure illuminated by the massive stars within the nebula. This work provides an unprecedented view of the spatially resolved physical and chemical properties, including density, temperature, ionization structure, heating processes, ionization gradients, and dust grain destruction. By capturing the complete picture of the Orion Nebula, the LVM bridges the gap between resolved Galactic studies and extragalactic investigations. This work offers a robust framework for understanding better the interplay internal physical phenomena and the global interstellar medium. In this talk, I will present the LVM's results on the physical and chemical properties of the Orion Nebula, highlighting its internal processes and implications for broader astrophysical studies. |
9:42 AM | Modeling the Multi-Phase ISM Shaped by Star Formation and Feedback in the LMC | Xinyue Liang |
The small-scale processes of star formation and feedback are tightly linked to galaxy evolution through a multi-scale matter cycle. During this cycle, stars form from the interstellar medium (ISM), and reshape it by injecting energy, momentum and metals, completing a feedback loop. The duration and the efficiency of the successive stages of this cycle vary across and within galaxies, but the exact physical mechanisms driving it remain elusive. Increasingly detailed ISM models and multi-wavelength observations now enable us to build a comprehensive view of this multi-scale cycle and of its impact on galaxy evolution. As our nearest neighbor, the Large Magellanic Cloud (LMC) has been observed in a broad range of wavelengths and offers the perfect combination between high spatial resolution and a large field of view. It is the ideal laboratory to examine in detail the interplay between stellar activity and the ISM. I will present a detailed study of the multi-phase ISM of the LMC using multi-wavelength tracers (including Halpha, OIII, SII, HI, 24 μm, CO), tracing all phases of the ISM, from the ionised to the molecular gas. By using MULTIGRIS, a new Bayesian code designed to constrain multi-component ionization models, I have determined key physical parameters of HII regions (e.g., density, ionization parameters, escape fractions of ionizing photons). These new constraints constitute a crucial step towards understanding how, and under the influence of which physical mechanisms, does the multi-phase ISM structure change, as an individual star-forming region evolves through a cycle of cloud formation, star formation and feedback. Leveraging new data obtain from LVM at high spatial resolution (~10 pc) will allow us to build upon our current work by providing additional insights into the ionized ISM, leading to a more comprehensive picture of its structure and evolution. Understanding how the detailed physical processes driving this cycle on ~10pc scales regulate the global, galactic-scale properties will serve as a major reference for studying feedback in high-redshift galaxy, where spatial resolution is far more limited. |
9:54 AM | Studying the Impact of Stellar Feedback with LVM: An Early Look at SMC HII Region N66 | Maren Cosens |
Feedback from star formation is thought to be one of the primary factors in setting the low observed star formation efficiency in molecular clouds by disrupting the gas and suppressing subsequent star formation. However, the impact of each feedback mechanism (e.g., direct radiation, warm gas pressure, stellar winds, supernovae explosions) in different environments is not fully understood. Optical IFSs are key tools for studying the ionization conditions and kinematics of the gas in and around H II regions, particularly when paired with the high spatial resolution made possible by observing local galaxies. I will present here a detailed look at the SMC HII region N66 observed with the SDSS-V Local Volume Mapper (LVM) which provides IFS observations from ~3600-9800A at R~4000 and ~10pc spatial sampling at the distance of the SMC. N66 is the brightest HII region in the SMC, associated with the well studied star cluster, NGC346, hosting over 30 massive O stars. This makes N66 an ideal region to connect observations of stars, HII regions, and the larger ISM by comparing the sources of feedback with their impact on the ionized gas we observe with LVM. However, the LVM will observe much more than this single HII region. By the surveys completion, it will have covered a large swath of the southern Milky Way midplane, a sample of nearby galaxies, and the full optical extent of the LMC and SMC. This makes LVM well positioned to study not only the sources and impact of star formation feedback in detail on cloud scales, but also to connect this to the conditions throughout the galaxy on kiloparsec scales. I will discuss how this initial look at N66 will help us prepare to extend our study of the impact of different modes of stellar feedback to this extensive sample. |
10:06 AM | Resolving Physical Conditions in Star Forming Regions with SDSS-V LVM | Natascha Sattler |
The chemical abundance of the interstellar medium (ISM) sets the initial conditions for star formation and provides a probe of chemical galaxy evolution models. Since metals act as coolants in the gas, we can obtain the gas abundances of HII regions by measuring the electron temperature through emission lines. If the electron temperature is not homogeneous across an HII region due to winds, shocks or different ionizing sources, then the abundances of any integrated HII region would be systematically underestimated. In our study, we use the SDSS-V Local Volume Mapper (LVM) to spatially map the physical conditions of the Trifid Nebula (M20) at approximately 0.24 pc resolution. This HII region is ionized by the single O7.5 V star HD 164492A, making it the ideal laboratory for probing spherical symmetries inside a single Strömgren Sphere. Using the different emission lines measured with LVM (e.g. Hydrogen recombination lines and collisional excited lines: [OII]3727,29; [OIII]4363; [OII]4650; [SII]4069; [SII]4076; [OIII]5007; [NII]5755; [SIII]6312; [NII]6584; [SII]6717,31; [OII]7320, [OII]7330; [SIII]9531) we compute spatially resolved maps of electron densities, temperatures, and ionic abundances. There we find internal variations and gradients in electron density that may result from ionization fronts. The electron temperature and the total oxygen abundance however look quite homogeneous. Moreover, we compare these spatially resolved properties with equivalent measurements of the integrated Trifid Nebula and find no significant variations between integrated and spatially resolved conditions in this rather simple HII region. We continue with this work on the more complex region of 30 Doradus. The LVM will finally observe around 260 such regions, providing a systematic overview of how unresolved nebular structures impact our integrated (extragalactic) prescriptions, especially in more complex ionized structures. |
10:18 AM | Unraveling the Magellanic Clouds with Different Diagnostic Diagrams | Alejandra Lugo |
In this work, I will present data from the Local Volume Mapper (LVM) analyzed with the data analysis pipeline (DAP). Specifically, I exploit the information of the galaxies: Magellanic Major Cloud and Minor Magellanic Cloud at different spatial resolutions (9 pc, 36 pc and 144 pc) in the use of different diagnostic diagrams such as BPT, WHAN and WHaD, with the aim of identifying and selecting different ionization sources. Working with IFU-type data, I can work with spatially resolved and integrated information, or focus on specific areas such as star formation regions. |
10:30-11:00 AM | Coffee |
11:00-12:30 PM | Session 5 | Chair: Maren Cosens |
11:00 AM | The Local Volume Mapper Data Analysis Pipeline: State of the Art | Sebastian F. Sanchez |
We present the state-of-the-art of the LVM-DAP, describing its work flow, the algorithrms, illustrating the results and describing the dataproducts. In addition we show the plan for validating the results, the possible future developments and the known problems (and foreseen ones). |
11:12 AM | Enhancing LVM Discoverability Through Interactive Data Visualization | Ivan Katkov |
The Local Volume Mapper (LVM) is rapidly progressing and will soon deliver science-ready spectra for a substantial fraction of the sky, opening diverse opportunities for scientific discoveries. This is an ideal moment to explore how the scientific impact of LVM data can be maximized through highly accessible and intuitive visualization tools. In this context, I will present my work on the interactive LVM data visualizer (LVMVIS), highlighting its current capabilities and outlining potential areas for future expansion. I invite discussion on how these ongoing efforts can better support the diverse scientific goals achievable with the LVM survey. |
11:24 AM | HeII Emission and its Connection with Stellar Sources in Magellanic Clouds | Evgeniya Egorova |
HeII emission serves as a valuable diagnostic for assessing the hardness of ionizing radiation. However, its origin in low-metallicity environments remains poorly understood. Using the SDSS-V/LVM IFU, we have detected the faint nebular HeIIλ4686 line across the disks of both the Large and Small Magellanic Clouds. In this talk, I will present our findings on the potential sources of HeII emission, such as Wolf-Rayet stars, and explore the physical properties of the HeII-emitting nebulae identified with LVM. Additionally, I will examine the implications of our results for the detection of HeII emission in unresolved studies of galaxies with properties similar to those of the Magellanic Clouds. |
11:36 AM | Phylogenetic Trees as a Tool for Stellar Evolution: Mapping Omega Centauri’s Chemical History | Sorya Lambert |
Globular clusters are powerful tools for understanding our galaxy’s formation and evolution, preserving chemical and dynamical signatures of past interactions. As some of the oldest and most massive stellar systems, they act as stellar fossils, offering insights into the Milky Way’s early epochs. Studies have revealed their complexity, with multiple stellar populations reflecting intricate star formation histories. Omega Centauri, the largest and most massive globular cluster, is a key example, showcasing multiple stellar populations with distinct ages, metallicities, and kinematics. Phylogenetic trees are widely used in biology to underline evolutionary relationships between species, identify common ancestors and evolutionary pathways. Since stars in a galaxy form out of material ejected from previous generations, it is an intriguing idea that we can use phylogenetic trees to understand the evolution of stars, and thus of galaxies. Stars formed in the same environment over a long period of time show a gradual variation in their chemical enrichment, whereas stars accreted from external sources display different properties, leading to distinct branches in the phylogenetic tree. Thus, this method will help to better understand evolutionary and merger histories of galaxies. While this idea has been successfully applied to individual stars in the Milky Way, our next step is to understand how it works with unresolved populations in nearby galaxies. Omega Centauri is a perfect example, being nearby and extensively studied through both resolved and unresolved spectroscopy. Using IFU spectroscopic data from the SDSS-V Local Volume Mapper we study stellar populations across the entire cluster. We build phylogenetic trees to trace evolutionary pathways within the cluster and explore its hierarchical assembly history. By applying a genetic method to stellar evolution, we highlight hierarchical connections between stellar populations, tracing their formation history and chemical evolution. I will present the techniques, our phylogenetic trees and interpret early results. |
11:48 AM | The Rosette Nebula with LVM and MWM: Morphological and Kinematical Structure | Monica Villa |
The Rosette Nebula (RN) is a well-studied HII region, flanked by an active Giant Molecular Cloud, making it an ideal laboratory for studying star formation. The HII region was formed by the winds from the OB association NGC 2244. We analyze the morphology and kinematics of the region, comparing the ionized and molecular gas, along with dust and the young stellar component. We use a set of new large scale IFU maps from the SDSS Local Volume Mapper, along with stellar atmospheric parameters and radial velocity data from SDSS APOGEE and Milky Way Mapper. We examine the spatial distribution of emission lines (Hα, Hβ, [OIII], [NII], [SII]) and line ratios (Hα/Hβ, [OIII]/Hβ, [NII]/Hα, [SII]/Hα) in relation to the molecular cloud, identifying ionized structures and interaction zones. We also make a comparative analysis of the velocity distribution of Hα, molecular gas, and stars, to understand the influence of stellar associations on gas dynamics and the influence of the local environment in the early evolution of the clusters. Our approach aims to reveal how NGC 2244 have impacted the molecular cloud and shaped the region’s evolution. |
12:00 PM | Improvements in FPS Fiber Positioning | Conor Sayres |
In the 2024 SDSS-V collaboration meeting in New Mexico, a breakout session was devoted to discussion surrounding the challenge of accurately placing robotic fibers on sky to maximize FPS survey throughput and spectrophotometry. Significant gains on this front have been made since then, and I will describe our current calibration procedures and present where we currently stand on this front. |
12:12 PM | The Sloan Digital Sky Survey Target of Opportunity Observing Mode | Jessie Runnoe |
The time-domain era has seen the proliferation of astronomical surveys to probe the transient and variable sky. Such surveys continue to reveal physical insights about the diverse classes of objects that exhibit changes in brightness on human timescales, from supernovae to accretion changes around supermassive black holes. Regardless of the original discovery or monitoring survey, spectroscopy often has a critical role to play in this field, especially in delivering classifications, redshifts, and kinematics for variable sources. But not all of the events and behaviors that would benefit from spectroscopic observations can be predicted, and as a result a new observing mode has gained popularity: target of opportunity (ToO) observations. ToO programs define in advance the triggers (i.e. conditions) needed to observe specific behaviors of interest and thereby achieve scientific goals. Recently, in the fifth iteration of the Sloan Digital Sky Survey (SDSS V) we have begun developing a new ToO program. This talk will give an update on the capabilities of this new observing mode and its implementation in SDSS V. |
12:30-1:30 PM | Lunch | |
1:30-2:00 | FPS Survey Plan Revision | Boxima Meeting room |
2:00-4:05 PM | Session 6 | Chair: Amy Rankine |
2:00 PM | Status of the BHM-Cluster Program | Johan Comparat |
In this presentation, I detail the BHM-cluster program and its current status. |
2:12 PM | An Exploratory Study of GUA & ASQOSS Quasars | Shir Aviram |
Quasars provide insights into the physics & evolution of supermassive black holes (SMBHs), galaxy evolution, and cosmology. I will present an exploratory study of quasars observed through two non-core BHM programs, designed to create a large, all-sky quasar catalog that would bridge gaps in previous quasars samples. The two programs, dubbed Gaia-UnWise AGN (GUA) and All Sky Quasar Optical Spectroscopic Survey (ASQOSS), are based on Gaia and WISE photometry, provide a highly efficient way to select quasars across the sky (>89% survey purity), with over 90,000 spectroscopically confirmed quasars observed to date, including tens of thousands of newly identified quasars in the southern hemisphere. The sample reaches redshifts up to z~5, and my detailed spectral analysis shows it covers a wide range of luminosities, black hole masses, and accretion rates. The distributions of these properties are highly consistent with previous SDSS quasar catalogs, establishing a robust reference for future southern and/or time-domain surveys, while enhancing and complementing our understanding of quasar demographics and SMBH evolution. |
2:24 PM | The Index Diagram. An Innovative and Efficient Method to Determine the AGN-HG Contribution | Alenka Negrete |
We present a computationally low-cost, novel and efficient method to determine the contribution of the stellar component from the host galaxy to the spectrum of an AGN. The method is based on the measurement of two indexes, Hb and the CaII H-band which is dominated by the stellar contribution when the HG dominates and by Hepsilon when the AGN dominates. This diagram separates the spectra into three groups: HG-dominated (HGD), intermediate and AGN-dominated (AGND). The spectral differentiation of the HGD and intermediate groups allows for better control over the subsequent use of programmes to separate the stellar continuum in detail. We also show that the locations of our three groups coincide with specific regions in the diagrams colour-z and the quasar main sequence. |
2:36 PM | Spectroscopic and Host Properties of X-ray Selected Red Quasars | Paloma Guetzoyan |
Supermassive Black Holes (BHs) can be hosted within the most luminous objects of the Universe called quasars. They are typically identified by their strong UV emission and blue colours. However, a sub-population has recently been discovered showing broad emission lines while displaying significantly reddened optical continuum - commonly referred to as red quasar. An ongoing effort has been made to uncover the origin of this reddening and the physical implications of such objects. Are red quasars a phase in the life cycle of AGN, part of a common evolutionary sequence? Are their intrinsic properties different? What about their host galaxy? In this project, we specifically explore differences, if any, between SDSS X-ray selected blue and red quasars. We carefully derive stellar masses through SED fitting by building a large photometric catalogue and accounting for AGN contribution. For spectral analysis, we use Independent Component Analysis (ICA) to reconstruct our spectra with no assumptions on continuum or line profile, while correcting for reddening. Preliminary results show that while both blue and red X-ray quasars seem to be found across a broad range of stellar masses and luminosities, red quasars tend to be more prevalent in higher mass galaxies, as well as being X-ray weaker. We also investigate differences in BH mass, eddington ratios, specific BH accretion rate and SFRs. If a slower growth rate seems to be observed for red quasars, it is still to be determined whether their host follow a similar trend in their star formation, showing that red quasars could potentially be hosted in galaxies transitioning to a quiescent state. |
2:48 PM | Insights from the Optical Spectra of X-ray-selected AGN in eFEDS | Catarina Aydar |
Multiwavelength information is crucial for a complete understanding of the observable Universe. In the era of big data, large-number statistics is the ideal tool to characterize the demography of galaxy populations and understand the complex phenomena involved in galaxy evolution. Therefore, SPIDERS (Spectroscopic Identification of ERosita Sources) selected objects identified in X-rays with eROSITA to be observed in the optical domain by SDSS-V. This survey allows us to compare physical properties obtained from optical and X-ray spectra, and I will present the results for 13,000 Active Galactic Nuclei (AGN) observed in the eFEDS field, one of the largest uniformly selected X-ray AGN samples observed in optical. We will study the relation between the black hole growth and the host galaxy by comparing properties such as black hole mass, accretion rate, luminosity, outflow rates, column density, etc. For a subsample of AGN with redshift lower than 1, we will present results of accurate AGN-host spectral decomposition that reveal properties from the host galaxy (such as star formation history, stellar mass, and the age and metallicity of the stellar populations) and their connection with AGN. Some insights about AGN spectra will also come from the challenges of performing the fit of this X-ray-selected sample. |
3:00 PM | Tracking the X-ray Evolution of On-going SDSS-V Changing-look AGN | Mirko Krumpe |
We are using XMM-Newton and Swift to follow the X-ray and UV evolution of the ongoing optical transition of Changing-look AGN discovered within SDSS-V. XMM-Newton will deliver X-ray spectra in its visibility windows, while Swift provides X-ray flux constraints in the time between. The obtained X-ray, UV, and optical datasets will explore how the X-ray corona, accretion disc, and broad-emission line region interact with each other. It will deliver valuable insights into how accretion flows evolve during AGN ignitions and depletions. We will compare our results with the outcomes of a program on X-ray-selected changing-look AGN. |
3:12 PM | Investigating the Connection Between AGN Colors and Obscuration: Insights from SDSS and eROSITA | Carolina Andonie |
The Sloan Digital Sky Survey (SDSS) has repeatedly observed the eROSITA Final Equatorial Survey (eFEDS), providing optical spectroscopy for ~12,000 X-ray sources. Motivated by studies linking AGN obscuration to the optical-to-MIR color r−W2 (Hickox et al. 2007; Andonie et al. 2025, submitted), I use SDSS spectra to examine how AGN optical properties vary with r−W2r−W2 (i.e., obscuration) as a function of redshift. To do this, I stack optical spectra in bins of r−W2r−W2 and redshift and fit them using PyQSOfit, incorporating components for the host galaxy, AGN, and absorption and emission lines. At z < 0.5 z < 0.5, we find that optical spectra are dominated by host galaxy emission, and r−W2 does not always correlate with dust extinction. However, at z > 0.5, r−W2 is strongly correlated with dust reddening. As expected, broad emission lines (e.g., Hβ, Hγ, Mg II, C III]) systematically decrease in flux with increasing r−W2, indicating growing dust extinction toward the quasar. Interestingly, the same trend is observed in narrow lines (e.g., [O III], [O II], narrow Hβ, [Ne III]), suggesting that the narrow-line region is more compact and closer to the SMBH than previously thought. I will also present X-ray spectral constraints and optical photometric properties of the sample. Finally, I will discuss how color selection can identify different AGN populations, which will be crucial for analyzing the hundreds of thousands of optical spectra being observed by SDSS-V as part of the Black Hole Mapper program. |
3:24 PM | Rapid best-model selection for spectral fitting: Exploring properties of variability selected AGN candidates (Remote) | Santiago Bernal |
Active Galactic Nuclei (AGN) are objects that exhibit variability on timescales ranging from hours to years across the entire electromagnetic spectrum. This property allows for the identification of AGN candidates in photometric surveys, such as the Zwicky Transient Facility (ZTF). We used a robust variability-based AGN classifier (the ALeRCE light curve classifier) to select AGN candidates by utilizing the ZTF alerts stream together with public photometric data. Here, we present results for thousands of these candidates, which have been observed by the SDSS Black Hole Mapper survey as part of the Open Fiber program 033. To validate the effectiveness of our selection, we assessed the fraction of confirmed AGNs based on the SDSS pipeline. We found that, out of 4.068 spectra with ZWARNING= 0, SN_MEDIAN_ALL>= 2, 3.743 (i.e. 92%) were classified as QSO, Galaxy-AGN or Galaxy-AGN BROADLINE. Following this validation, we implemented a novel method based on the Discrete Wavelet Transform and applied to the residuals of the spectra best-fit. This method provides an automatic, fast and reliable solution for the best-model selection and the analysis of AGN spectra. Using this approach, we report the results for the distributions of broad emission lines (BELs) equivalent-width, BELs FWHM, bolometric luminosities, black hole masses, accretion rates, AGN-continuum slopes, and narrow emission lines ratios (in the form of BPT-diagrams classification) for these 3743 candidates. These results also serve as a quality control for the 4MOST-ChANGES survey, which will target 1.5 millions of AGN candidates selected by variability. |
3:36 PM | Reverberation Mapping 101: Using Light Echoes to Explore the Centers of Active Galactic Nuclei (Remote) | Kate Grier |
The SDSS-V Black Hole Mapper is carrying out an industrial-scale reverberation mapping campaign to measure black hole masses in hundreds of quasars. In this presentation, I will introduce the idea of reverberation mapping and its applications and summarize recent progress and questions within the field of reverberation mapping, as well as report specifically on the status of the BHM Reverberation Mapping project. |
4:05-5:15 PM | Poster Session |
Poster 1 | eROSITA-detected M dwarfs in the Gaia color-magnitude diagram: evidence for youth, binarity and super-solar metallicity | Beate Stelzer |
The recent all-sky surveys with eROSITA on the Spektrum-Roentgen-Gamma satellite have provided statistical samples of X-ray emitting low-mass stars. A notable observation is that the distribution of X-ray emitting M dwarfs in the Gaia color-magnitude diagram is skewed upwards of the stellar main-sequence. Assuming constant X-ray to bolometric luminosity, called saturation, X-ray bright stars are expected to be optically more luminous, and their peculiar position in the HR diagram points at a bias due to the flux limit of X-ray surveys. This bias can be turned around into a tool for identifying young stars in the solar neighborhood. Specifically, we present here a sample of ~700 nearby M dwarfs detected in the first eROSITA all-sky survey, eRASS1. We search for the cause of their "overluminosity" in the Gaia color-magnitude diagram. We use the Gaia RUWE parameter to identify potential binary stars and Gaia astrometry and radial velocities to calculate UVW space motions. We find from a match with the MOCA (Montreal Open Clusters and Associations) database that about 20% of the eRASS1-detected M dwarfs are known members of a young stellar association with ages of ≈20 to 150 Myr. About 30 additional stars were identified through our analysis to have space motions and/or positions consistent with a known young moving group (MG) but have not been recognized before as members. We compare the MG ages we obtained for the individual stars to their isochronal ages from evolutionary models. Finally, we examine the possible influence of metallicity on the position of the stars in the color-magnitude diagram and how this interferes with the age estimate. Systematic spectroscopic follow-up would be beneficial for a better characterization of the population of X-ray emitting M dwarfs. |
Poster 2 | Unveiling Orbital Periods in Cataclysmic Variables: A TESS Variability Study of SDSS-V/eROSITA Sources | Santiago Hernández |
Determining the orbital periods of Cataclysmic Variable stars (CVs) is essential for the confirmation of candidates and for the understanding of their evolutionary state. The Transiting Exoplanet Survey Satellite (TESS) provides month-long photometric data, enabling a systematic period analysis of these systems. In Hernández et al. (in prep.), we conducted a systematic search for orbital periods in a sample of magnetic cataclysmic variables (mCVs) using TESS two-minute cadence light curves. This study demonstrated that TESS light curves can efficiently be used to determine orbital periods in CVs. Additionally, we developed a methodology to assess the reliability of period detections in TESS light curves. In search for new CVs with low-mass donors, we have matched the eROSITA catalogs with the white dwarf catalog from Gentile Fusillo et al. 2021. Using the scorecard described in Muñoz-Giraldo et al. 2024, 321 WDs were selected as CV candidates with low-mass donors, of which 81 have been observed in SDSS-V. The SDSS pipeline classifies only 13 of them as CVs or CV candidates, but the full sample is currently undergoing more detailed vetting. Here we use our period detection methodology to search for periodic variability in this sample, as an additional evidence in favor or against the CV nature of these stars. |
Poster 3 | Simulating the non-accreting white dwarf population in eROSITA data | Susanne Friedrich |
The first all-sky X-ray survey was performed by the ROSAT X-ray observatory in the 0.1–2.4 keV energy range (Trümper 1982). It was not until almost 30 years later that an all-sky X-ray survey was to be carried out again with the SRG/eROSITA X-ray mission. Between December 2019 and December 2021 four all-sky surveys were completed. We have already shown that it is possible to detect white dwarfs in eROSITA data: almost 300 white dwarfs from the Gentile-Fusillo catalogue (Gentile Fusillo et al. 2021) with a 90% probability of being a white dwarf were found; some of them only by processing eROSITA data with a lower energy threshold of 0.1 keV instead of 0.2 keV (Friedrich et al. 2025). Here we present simulations with a lower energy threshold of 0.1 keV to optimize data processing to maximize the number of white dwarfs that can be detected in the eROSITA data. If successful, we plan to reprocess eROSITA data with this lower energy threshold of 0.1 keV to increase the number of white dwarfs detected in the X-ray range and complement the data from SDSS-V and GAIA. |
Poster 4 | Supernova remnant in the Large Magellanic Cloud with eROSITA | Federico Zangrandi |
Supernovae (SNe) explosions at the end of the life of a star expel the stellar material in the surrounding which enrich the interstellar medium (ISM) with metals. The interaction between the the shock wave and the ISM produce supernova remnants (SNRs). Their emission is visible in different wavelength from radio, optical to X-ray. SNRs can be studied to infer information about the explosion itself and on the property of the surrounding ISM. SNRs are responsible for injecting energy into the ISM and therefore influence the evolution of the entire host galaxy. A complete sample of SNRs inside a galaxy is important to understand the chemical enrichment and the energy budget inside a galaxy. The best laboratory for the study the SNRs population in a galaxy is the Large Magellanic Cloud (LMC), which is the nearest star-forming galaxy with low absorption along the line of sight. The extended Roentgen Survey with an Imaging Telescope Array (eROSITA) on board Spektrum-Roentgen-Gamma (Spektr-RG, SRG) in X-rays is the best instrument available to study the emission of SNRS due to the large field of view and the high sensitivity in the softer part of the X-ray emission. However a synergy with observations at other wavelengths is fundamental to have a comprehensive understanding of the SNR sample in a galaxy. Thanks to the complete coverage of the LMC and its surroundings in the eROSITA all-sky survey and the use of multi-wavlength data we increased the sample of known SNRs and SNR candidates in the LMC. We have detected more SNRs on the outskirts of the LMC which we investigated further in a XMM-Newton follow-up. |
Poster 5 | Using Wolf-Rayet regions as a unique laboratory to study star formation and stellar feedback | Eric Liang |
The onset of star formation from molecular clouds and the details of stellar feedback to the interstellar medium (ISM) are among the most important yet unresolved mysteries in galaxy evolution. Wolf-Rayet (WR) stars are the post–main sequence stage of high-mass stars, with stellar ages of 2-10 Myr. Thanks to such short lifetime and their strong feedback, they are ideal sites to study star formation and stellar feedback. With Local Volume Mapper data, this project systematically searches for WR regions defined by their distinct spectral features. Combined with multi-wavelength data, this catalogue facilitates the following studies: (1) to understand the properties and destruction timescale of the parental molecular clouds of WR regions; (2) to look for evidence for stochastic sampling of the initial mass function in star cluster SED modelling by using WR regions as a precise and accurate age timer; (3) to put constraints on pre-supernova feedback (in metallicity, pressure, temperature, density, etc.) and to reveal the ISM properties immediately before supernova explosion. This poster presents the catalogue construction and showcases explorative investigation in these directions. |
Poster 6 | Update on improving the LVM DAP stellar continuum subtraction with VLT/XShooter spectra of OB stars in the Magellanic Clouds | Aida Wofford |
I will present the ongoing efforts towards improving the stellar continuum subtraction of LVM observations of the Magellanic Clouds. We are testing how the quality of this subtraction improves when we add to the current stellar library used by the Data Analysis Pipeline, OB-star spectra (which it currently doesn't have). The spectra are from the XShooter instrument on the Very Large Telescope and were obtained as part of the XShooting ULLYSES program. |
Poster 7 | Photometric light curve generation for the SDSS-V Black Hole Mapper Reverberation Mapping Project | Teddy Peña |
We are developing a photometric pipeline created in support of the Sloan Digital Sky Survey V's Black Hole Mapper Reverberation Mapping project (SDSS-V BHM-RM; Kollmeier et al. 2019). ~850 quasars over a wide range of redshifts (0.1<z<4.5) are currently under high-cadence spectroscopic and photometric monitoring, with the express purpose of black hole mass measurement through reverberation mapping. Expanding upon lightcurve work first completed by Kinemuchi et al. (2020), we are producing light curves with g/i band imaging from the Canada France Hawaii Telescope (CFHT), the Steward Observatory's Bok telescope (Bok), and the Wisconsin-Indiana-Yale-NOIRlab telescope (WIYN). While under active development, we will show key improvisations, lessons learned, and preliminary results from processing fresh data and archived images taken over a decade of observations. We will also outline implications and future goals for the analysis software. |
Poster 8 | The chemical evolution of the Milky Way thin disk using solar twins | Anastasiia Plotnikova |
A recent study by Nissen et al. (2020) has found a bimodality in the age-metallicity diagram traced by nearby solar-twin stars. Their results seem to agree with more recent studies based on APOGEE DR17 data (Jofré 2021; Anders et al. 2023). However, the actual presence of these populations in the thin disk is still a matter of debate. Several other studies, that used different age determination methods, observational data and cutoffs, show no signature of two populations (Xiang & Rix 2022; Lu et al. 2024; Miglio et al. 2021). In this study we address whether the age-metallicity relation (AMR) deviates from the expected trend of metallicity increasing smoothly with age. We also show the presence (or absence) of two populations, as recently claimed using a relatively small dataset. Moreover, we studied the Milky Way thin disk's chemical evolution using solar twins, including the effect of radial migration and accretion events. In particular, we exploited high-resolution spectroscopy of a large sample of solar twins in tandem with an accurate age determination to investigate the Milky Way thin disk age-metallicity relationship. Additionally, we derived the stars' birth radius and studied the chemical evolution of the thin disk. We discovered that statistical and selection biases can lead to a misinterpretation of the observational data. An accurate accounting of all the uncertainties led us to detect no separation in the AMR into different populations for solar twins around the Sun ( 0.3 < [Fe/H] < 0.3 dex). This lead us to the conclusion that the thin disk was formed relatively smoothly. For the main scenario of the Milky Way thin disk formation, we suggest that the main mechanism for reaching today's chemical composition around the Sun is radial migration with the possible contribution of well-known accretion events such as Gaia-Enceladus/Sausage and Sagittarius. |
Poster 9 | Discovering Radial Migration Patterns with Chemical Evolution Models | Christian Lehmann |
Stellar radial migration reshapes the distribution of stars in the Milky Way, carrying metal-rich stars to the outer Galaxy and metal-poor stars to the inner Galaxy. The metallicity of the interstellar medium near the Sun indicates that stars with super-solar metallicity ([Fe/H] > 0.1 dex) are too metal-rich to have formed locally. Our current understanding of these processes is informed only by the distribution of metals in stars and gas at the present day. To understand the connection between the dynamical evolution of the Galactic disk and its observed abundance structure, we turn to Galactic chemical evolution models. We use the Versatile Integrator for Chemical Evolution (VICE) to set up simple, fast, and easily adjustable models of Milky Way-like galaxies to incorporate physically motivated migration prescriptions, focusing primarily on structures such as spiral arms and the bar as the cause for radial migration. We explore the effects of adjusting the length, lifespan, and thickness of both spiral arms and the bar on chemical abundance distributions resulting from adjustments to the motions of stars. We inform these processes with current observations of radial velocities from Gaia to estimate migration probabilities. Introducing spiral arms only in the late stages of evolution leads to a minor reduction in the total amount of migration, but distributes stars of all ages much more evenly across the disk. By comparison, spiral arms that are present for the full duration of the Galaxy's lifetime lead to many old stars being found far from their birth environments. |
Poster 10 | The radial structure of the Milky Way as seen by APOGEE | Jianhui Lian |
The radial structure of a galaxy is one of the fundamental properties that reflects its growth and assembly history. {While it is straightforward to measure that of external galaxies, it is challenging for the Milky Way because of our inside perspective. Traditionally, the radial structure of the Milky Way has been assumed to be characterized by a single exponential disk and a central bulge component. In this talk I will introduce our recent work in which we report 1) a new measurement of the age-resolved Galactic surface brightness profile in an unprecedentedly wide radial range from R = 0 to 17 kpc and 2) the corresponding size of the Milky Way in terms of a half-light radius. We find a broken surface brightness profile with a nearly flat distribution between 3.5 and 7.5 kpc, in contrast to a canonical single-exponential disk. This broken profile results in a half-light radius of 5.75±0.38 kpc, significantly larger than that inferred from a single-exponential disk profile but in good consistency with local disk galaxies of similar mass. We also confirm that the size growth history of the Milky Way is broadly consistent with high-redshift galaxies but with systematically smaller size. Our results suggest that the Milky Way has a more complex radial structure and larger size than previously expected. |
Poster 11 | Chemical Fingerprints of Bursty Star Formation: Uncovering the Early Evolution of Dwarf Galaxies | Yuan-Sen Ting |
Star formation in dwarf galaxies is thought to occur in bursts, but directly observing this process in the early Universe has remained challenging. In this talk, I will present a new method for detecting episodic star formation by analyzing chemical abundance patterns in dwarf galaxies. We demonstrate that quiescent periods between starbursts create distinct gaps in the metallicity distribution due to continued iron enrichment from Type Ia supernovae. Using Gaussian mixture models, we can statistically distinguish these discontinuous chemical tracks from continuous star formation. Applying this technique to APOGEE observations of the Sculptor dwarf spheroidal galaxy reveals evidence for multiple star formation episodes separated by ~300 Myr quiescent periods. Our method provides unprecedented temporal resolution of early dwarf galaxy evolution, probing timescales inaccessible to traditional color-magnitude diagram analyses. These results have important implications for understanding both galaxy formation physics and the role of dwarf galaxies in cosmic reionization. I will discuss how upcoming spectroscopic surveys like SDSS-V will enable applying this technique across the dwarf galaxy population, opening a new window into the episodic nature of star formation in the early Universe. |
Poster 12 | Limitations on the Two-Infall Scenario in the Era of Large Stellar Age Catalogs | Liam Dubay |
Stellar populations in the Milky Way exhibit a clear separation into two chemically distinct populations that are separated by their [a/Fe] ratios. A popular explanation for this observation is the two-infall scenario, which postulates that two periods of substantial accretion rates dominate the assembly history of the Galaxy. However, most previous studies using the two-infall scenario have explored a limited portion of the parameter space, typically neglecting radial migration and assuming that the Galactic disk never ejected a substantial outflow. Thanks to advances in stellar age measurements in recent years, we can now also compare this popular model to more direct measurements of the Galaxy's evolutionary timescales from large stellar catalogs. We run multi-zone galactic chemical evolution (GCE) models with a two-infall-driven star formation history, radially dependent mass-loaded outflows, and a prescription for radial migration tuned to a hydrodynamic simulation. We compare our model results to abundance patterns across the disk from APOGEE DR17 and early data from the SDSS-V Milky Way Mapper program, supplemented with stellar age estimates through multiple methods. Although the two-infall scenario offers a natural explanation for the [a/Fe] bimodality, it struggles to explain several features of the age-abundances structure in the disk. The two-infall scenario generically predicts a massive and long-lasting dilution event, but the data show that stellar metallicity is remarkably constant with age across much of the Galactic disk. This apparent age-independence places considerable restrictions upon the two-infall parameter space. These issues can be mitigated, but not completely resolved, by allowing the accreted gas to be pre-enriched to low metallicity. |
Poster 13 | Impact of ⟨3D⟩ NLTE on GCE of oxygen with the RAdial Velocity Experiment | Guillaume Guiglion |
The stellar chemical abundances, coupled with stellar kinematics are a unique way to understand the chemo-dynamical processes that occurs to build the Milky Way and its local volume as we observe today. However, measuring stellar abundances are challenging as one needs to properly address the effect of departure from the local thermodynamic equilibrium, as well as the commonly used 1-dimensional model atmosphere. In this work, we constrain the chemical evolution of [O/Fe] in ⟨3D⟩ NLTE by using FG stars of the RAdial Velocity Experiment (RAVE). Using standard spectral fitting method, we determine for the first time LTE and NLTE abundances of oxygen from the O i triplet at 8446Å in turn-off and dwarf stars thanks to intermediate-resolution RAVE spectra, assuming both 1D and ⟨3D⟩ model atmosphere. Results. We find that NLTE effects plays a significant role when determining oxygen even at a resolution of R= 7500. Typical NLTE-LTE corrections of the order of -0.08 dex are measured in dwarfs and turn-off stars using 1D MARCS models. In addition, ⟨3D⟩ modelling significantly impacts the oxygen abundance measurements. In contrast to applying ⟨3D⟩ NLTE abundance corrections or the classical 1D LTE, the full ⟨3D⟩ NLTE spectral fitting yields improving the precision of abundances by nearly 10%. We also show that the decrease of [O/Fe] in the super-solar metallicity regime is rather characterised by a flat trend when [O/Fe] is computed in ⟨3D⟩ NLTE. We attribute this flattening at super-solar [Fe/H] to the interplay between locally born stars with negative [O/Fe] and stars migrated from the inner MW regions with super-solar [O/Fe], supporting the complex chemo-dynamical history of the Solar neighbourhood. This work is a test bed for the spectral analysis of the 4MOST low-resolution spectra that will share similar properties as RAVE spectra in the red wavelength domain. |
Poster 14 | Chemical Variation Across the Milky Way with Calibrated Abundances from APOGEE | Tawny Sit |
Stellar abundance measurements are subject to systematic errors that induce extra scatter and artificial correlations in elemental abundance patterns, which can pose issues when examining abundances across large samples of stars that span a range of stellar parameters. We derive empirical calibration offsets that remove systematic trends with surface gravity log(g) in 17 elemental abundances for 288,789 evolved stars from APOGEE DR17. We then fit these corrected abundances with a two-process model, representing each star's abundances as the sum of a prompt CCSN process and a delayed SNIa process, and the element-by-element residuals from this fit. Our catalog of calibrated abundances, two-process parameters, and residual abundances has proven useful for studying median residual abundance trends in open clusters, globular clusters, and dwarf galaxies (Sit et al. 2024), as well as examining low-amplitude variations across the Galactic disk (Griffith et al. 2024). Most recently, we used this catalog to investigate the origin of abundance variation in Milky Way disk stars on the high-α plateau. We find that stars with higher [Fe/Mg] ratios have higher [X/Mg] ratios in other iron-peak elements, and the observed trends of [X/Mg] with SNIa/CCSN ratio (inferred from a two-process model) are steeper for elements with a large SNIa contribution and flatter for elements with low SNIa contribution. Our results suggest that variation in SNIa/CCSN ratio is a significant source of intrinsic abundance scatter on the high-α plateau, and that the value of [Mg/Fe] corresponding to pure CCSN enrichment should be at least as high as the upper edge of the plateau ([Mg/Fe]≈0.35). We anticipate that our log(g) calibration method will be applicable to abundance measurements from Milky Way Mapper, enabling future studies of abundance patterns in various stellar populations and of additional enrichment processes that affect galactic chemical evolution using even more stars. |
Poster 15 | The SAGES survey and Stellar parameters of 21 million stars | Zhou Fan |
Precise stellar parameters are essential for understanding various nature of stars and our Milky Way galaxy. An increasing number of medium-band photometric surveys are presently involved in ascertaining stellar parameters. In this study, utilizing data from the Stellar Abundance and Galaxy Evolution Survey (SAGES), we employed the random forest algorithm to establish precise mappings from stellar colors and astrometric parameters to stellar parameters. The precision of [Fe/H] and logg attains an impressive 0.09 dex, while Teff achieves an accuracy of 60 K. These results are applicable to both giant and dwarf stars. Building upon this mapping, we furnish stellar parameters for over 15 million stars, constituting a foundational dataset for research the structure of the Milky Way, and identify metal-poor star candidates for ongoing and future spectroscopic surveys, such as SDSS-V. |
Poster 16 | StarFlow: Using Normalizing Flows to estimate stellar ages and distances | Alexander Stone-Martinez |
Understanding the ages of stars is crucial for unraveling the formation history and evolution of our Galaxy. Traditional methods for estimating stellar ages from spectroscopic data often struggle with providing appropriate uncertainty estimations and are severely constrained by the parameter space. In this work, we introduce a new approach using normalizing flows—a type of deep generative model—to estimate stellar ages for evolved stars with improved accuracy and robust uncertainty characterization. The model is trained on stellar masses for evolved stars derived from asteroseismology and predicts the relationship between the carbon and nitrogen abundances of a given star and its age. Unlike standard neural network techniques, normalizing flows enable the recovery of full likelihood distributions for individual stellar ages, offering a richer and more informative perspective on uncertainties. Our method yields age estimations for 378,720 evolved stars and achieves a typical absolute age uncertainty of approximately 2 Gyr. By intrinsically accounting for the coverage and density of the training data, our model ensures that the resulting uncertainties reflect both the inherent noise in the data and the completeness of the sampled parameter space. We also present a new version of this model that estimates stellar distances. |
Poster 17 | Near-IR spectra allow for robust identification of YSOs across the entire range of stellar parameters | Valentina Bonilla |
The Sloan Digital Sky Survey (SDSS) has collected spectral data for millions of stars, including approximately 100,000 pre-main sequence stars. Our project aims to refine stellar classification and confirm indicators of youth by thoroughly analyzing this extensive dataset. To ensure accuracy, we created a catalog of young stars observed by the APOGEE spectrograph, cross-referencing classifications across different wavelengths. This catalog served as the foundation for training a neural network to predict stellar youth, achieving a precision of 0.762 and a recall of 0.896. Notably, we expect that many of the predicted “false positives” are bona fide young stars, while “false negatives” could represent stars that are more evolved. To build upon these findings, we are conducting a detailed analysis of the fluxes of both predicted young and not-young stars, examining them across various ranges of surface gravity and effective temperature. This comprehensive approach allows us to identify specific spectroscopic features that are characteristic of young stars. By pinpointing these markers, we hope to establish a more traditional spectral-based method for identifying stellar youth, which could enhance classification techniques and contribute valuable insights into the characteristics of early stellar development. Ultimately, this research aims to advance our understanding of stellar evolution and the processes that govern the formation of young stars in the universe. |
Poster 18 | The SDSS DR19 catalogue of white dwarfs | Nicola Gentile Fusillo |
Over 95% of stars in our Galaxy share the same destiny: becoming a white dwarf. These slowly cooling remnants hold the key to the Milky Way’s formation history and serve as powerful tools across diverse astrophysical fields—from stellar evolution and exoplanet studies to extreme physics and the origins of Type Ia supernovae. However, white dwarfs are intrinsically faint and sparsely scattered across the entire sky, making them challenging and expensive to observe in large numbers. For over 20 years, the white dwarfs captured by SDSS —mostly serendipitously— have been the primary source for large-scale discoveries. While this data fueled groundbreaking research, the SDSS white dwarf sample is incomplete, strongly affected by biases and plagued by an impossible to decode selection function...that is until SDSS V and DR19. Today white dwarfs in SDSS are no longer just serendipitous discoveries, but science targets carefully selected from a mostly unbiased Gaia-based sample. I will present the work the compact object group has been doing in constructing a SDSS DR19 white dwarf catalogue mentioning some of the challenges we are facing and highlighting the most important features of this product. I will then conclude with a quick overview of the critical questions in the field of white dwarfs that will be addressed by SDSS V catalogues, from spectral evolution, to the origin of magnetic fields, and the study of planetary remnants. |
Poster 19 | Anomalous Redshifts in White Dwarf Radial Velocity Measurements from Low-Resolution Spectroscopy and Proposed Mitigation | Stefan Arseneau |
SDSS-V is the largest existing catalog of white dwarf spectroscopic data, enabling reliable radial velocity measurements from hydrogen Balmer lines of over 10,000 stars. Because of their extreme compactness, white dwarfs experience a substantial gravitational redshift (on average 30 km/s corresponding to a $0.6~M_\odot$ white dwarf) which can be measured statistically, leveraging SDSS's large sample size and providing unprecedented constraints on white dwarf stellar structure. This requires an accurate understanding of wavelength calibration in the BOSS spectrograph and of the shapes of hydrogen absorption lines which are heavily pressure broadened by the Stark effect. We show that substantial anomalous redshift (5-15 km/s) exist in radial velocity measurements made from observations at SDSS spectral resolution relative to similar measurements from high-resolution spectra which resolve the thermally-broadened NLTE core of the line. These anomalous redshifts exhibit a temperature dependence which appears correlated with partial ionization of hydrogen in the stellar photosphere. This indicates that some physics of line formation in high-density plasmas are not accounted for in state-of-the-art white dwarf model atmospheres. Additionally, we show that the wavelength calibration of BOSS spectra from SDSS-V is offset from those of previous generations of the survey. We provide corrections to account for these anomalous redshifts in a way that is independent of an assumed mass-radius relation, and we demonstrate that statistical measurements of gravitational redshift with these corrections yield improved agreement with theoretical mass-radius relations. Our results provide a set of best practices for white dwarf radial velocity measurements from spectroscopy at resolutions insufficient to resolve the NLTE core of Balmer lines such as those of SDSS. |
Poster 20 | Deconstructing the Low-Mass Main Sequence in Four Open Clusters with Hundreds of BOSS Spectra | Kayvon Sharifi |
Between January 7th and February 3rd of this year, the APOGEE instrument at LCO underwent servicing and a short BOSS-only program was implemented. A series of bright time-designs were made for targets in nine clusters (seven open and two globular), based on membership lists from Hunt & Reffert (2024). In clusters for which a significant portion of the low-mass main sequence could be observed, low-mass members were given priority. Clusters with large numbers of observable M dwarfs were Praesepe, NGC 2516, NGC 3532, and Trumpler 10. These designs allowed us to obtain spectra for ~2,000 unique red dwarfs and provide an opportunity to investigate why the lower mass main sequence appears unexpectedly broad in these clusters. To ensure a clean cluster sample, we leverage the full 6D kinematics made available by BOSS and Gaia to confirm their cluster membership. With the resulting cleaned cluster samples, we investigate whether the observed heavy thickening of the main sequence in the M dwarf regime may be attributed to age dispersion, metallicity differences, stellar multiplicity, or chromospheric activity level variations within each cluster. These spectra represent the deepest exploration of low-mass optical spectra in open clusters in SDSS-V. |
Poster 21 | Sparsely Sampled Radial Velocity Curves in SDSS: When Quantity has a Quality of its Own | Carles Badenes |
Through the years, SDSS has collected repeat spectroscopy of hundreds of thousands of stars, sampling all the phases of stellar evolution, from the Main Sequence to the Red Giant Branch, through the Red Clump, and all the way to degenerate White Dwarfs. Although the vast majority of these Radial Velocity Curves do not have enough points to derive a full orbital solution, thousands of them can effectively constrain the multiplicity statistics of the underlying stellar populations, including the binary fraction and the period distribution. Furthermore, a direct comparison between the RVs measured by SDSS and models generated with Binary Population Synthesis codes has the potential to validate or rule out key uncertain mechanisms in the evolution of interacting binaries, like the efficiency of mass transfer and the outcome of common envelope evolution. We will discuss recent results using a sample of White Dwarf Main Sequence binaries observed by SDSS/APOGEE. |
Poster 22 | Moving and Grooving: Early Results on Many-Epoch Radial Velocities of Red Giant SDSS-V | Joleen Carlberg |
SDSS-V is obtaining multi-epoch infrared spectra of stars across the HR diagram. The binary working group aims to get 12+ epochs for stellar types of particularly interest, including red giant stars. By both intentionally leveraging legacy SDSS-III and SDSS-IV data and defining cadence requirements requiring both short and long spaced observations in SDSS-V, we can probe astrophysical processes on time scales from days to decades. Here, we highlight some early results for red giant stars that have already achieved many high quality epochs of data, showcasing intrinsic stellar variability on the upper red giant branch and long period companions in a subset of well-characterized stars. |
5:15 PM | Transportation (change of venue) |
6:30 PM | Conference Dinner | Urban Kitchen |
7.30 PM | Director’s Speech | Juna Kollmeier |
8:00-9:00 PM | After SDSS-V (AS5) discussion | Peter Frinchaboy |
Wednesday June 4th 2025 |
8:30 AM | Transportation |
9:00-10:30 AM | Session 7 | Chair: Catarina Aydar |
9:00 AM | BHM 101: Extreme Variability and Transient Phenomena in Active Galactic Nuclei | Benny Trakhtenbrot |
Active galactic nuclei (AGN) are powered by supermassive black holes (SMBHs) that accrete matter, typically on timescales that could last hundreds of Myr. The emission that emerges from the accretion process ultimately covers most of the accessible electromagnetic spectrum and is known to show stochastic variability on levels of ~10% over a wide range of timescales (days to decades). This variability allows us to measure the masses of the black holes, to probe their immediate surroundings, and to better understand how these compact objects can affect their entire host galaxies. The renaissance in time-domain astronomy, which thanks to SDSS-V includes systematic spectroscopic monitoring of thousands AGN on various timescales, reveals a more dynamic and extreme temporal landscape: SMBHs that appear to be turning “off” or “on”; complex gas motions around the SMBHs; newly launched and accelerated outflows; and other phenomena which we’re still struggling to understand (or even just to quantify). In this “101” talk I will describe how the various programs within SDSS-V, including “core” BHM programs and “open fiber” ones, are designed to survey this new & exciting landscape, and will review some of the relevant projects and results. As the most “extreme” phenomena are rather rare, we’re bound to reveal more of them as we accumulate data. I will therefore also mention a few of the outstanding challenges that we’re facing in our attempts to identify extreme AGN spectral variability, to put it in context, and to interpret it. |
9:30 AM | Search for Changing-look AGN by cross-matching HETDEX and SDSS | Chenxu Liu |
HETDEX is an untargeted optical spectroscopic IFU survey which would benefit the Changing-look AGN sample with a more complete dimming AGN population. We extracted the HETDEX spectra at the SDSS DR16Q AGN. There are 8034 SDSS QSOs covered by HETDEX fibers within 1 arcsec. We require a psudo-g mag difference of the two spec epochs to be at least 1 mag or the line flux ratio F_bright/F_dim > 2 giving a 913 CL AGN candidate parent sample. We collect archival photometric light curves from CRTS, PS1, ZTF, and Mephisto and did VI checks to identify potential issues. Here are our preliminary findings: After VI, 205 CL AGN are confirmed: 135 are brightening ones, and 70 are dimming ones, roughly giving a brightening over dimming ratio of 2:1 at the redshifts we probe (z~1.5). (2) There are only a few among the 205 CL AGNs show significant line width changes (type 1.X > type 1.Y) suggesting changing of the obscuration might not explain the majority of the population. (3) The dimming AGN tend to be more massive than both the parent sample and the brightening AGN. (4) The time scale of the CL AGN are typically a few (< 10) years, significantly shorter than the viscous inflow time scale, suggesting either the magnetic fields accelerated gas flows are there or the variabilities come from thermal instabilities. (5) Dimming AGN slightly prefer lower Eddington ratios. We would like to add SDSS V spectra to the above analyses to better evaluate the potential relation between the variabilities and the physical parameters. |
9:42 AM | The H𝞫 Variability of SDSS Quasars | Collin Dabbieri |
Current spectroscopic searches for Supermassive Black Hole Binaries are limited by our incomplete statistical understanding of how broad line regions (BLRs) vary in the normal quasar population, particularly on timescales corresponding to the BLR’s dynamical times. Fortunately, the ongoing spectroscopic monitoring campaigns initiated during SDSS IV now provide us with sufficient data to develop this crucial characterization, which will also serve as the benchmark for physical models which seek to describe physical changes in the BLR. To this end, we created a catalog of spectroscopic variability properties for all spectra for quasars with z<0.8 and at least two spectroscopic observations included in the SDSS Data Release 16 quasar catalog. For each pair of spectra in this sample, we calculated the change in radial velocity of the centroid of broad H𝞫 emission, otherwise known as radial velocity jitter, as well as other derived properties related to broad H𝞫 shape variability. We utilized forward-modeling methods to develop a new method for estimating the uncertainty in the jitter in the case where a spectral decomposition is used to isolate the broad H𝞫 emission. I will present structure functions for broad H𝞫 profile variability and discuss the implications of our results for our understanding of the structure and dynamics of the BLR. |
9:54 AM | Exciting Prospects for the Study of Extremely High Velocity Outflows in SDSS Quasars | Paola Rodriguez Hidalgo |
Outflows launched from the vicinity of supermassive black holes are among the most promising candidates for linking the small and the large scale phenomena in Active Galactic Nuclei. A recently discovered class of outflows, extremely high velocity outflows (EHVOs), may be key to understanding feedback processes, as it is likely the most powerful in terms of mass energy, given their speeds exceeding 10% of the speed of light. EHVOs have been observed across a wide range of redshifts, including several cases among the few known quasars at z > 7. In two recent projects, my research group — composed primarily of undergraduate students at a minority-serving institution — has identified almost 140 new cases, enlarging the previously known sample by a factor of 20. This expansion is allowing us to carry out several investigations not accessible before. I will discuss the results of these studies, including (1) evidence that EHVOs predominantly appear in quasars where the CIV emission line exhibits larger blueshifts, providing the first indication that quasars with EHVOs also show outflows in emission, and (2) how they seem to appear in quasars with distinct properties — such as bolometric luminosity and Eddington ratio — compared to their lower-speed counterparts, the well-studied population of BALQSOs. Finally, I will present our latest findings on EHVO variability and the results of theoretical simulations that help us determine the location of these outflows and the conditions required for their launch. Understanding how EHVOs evolve over time and across the history of the universe, particularly now that they are being detected at very high redshifts, may be crucial for solving the puzzle of galaxy evolution. |
10:06 AM | Peering into the Inner Parsec of a Highly-Variable AGN | Zach Stone |
To constrain the growth of supermassive black holes (SMBHs), it is imperative to accurately and unbiasedly measure its mass over cosmic time. SMBH masses are frequently measured via active galactic nuclei (AGNs), exploiting their temporal variability. Most SMBH masses are obtained with the reverberation mapping (RM) method, assuming viriality of the gas immediately surrounding the SMBH. RM assumes that a central source around the SMBH emits photo-ionizing radiation, which is then absorbed and re-emitted towards the observer. Dynamical modeling is an advanced type of RM, used to simultaneously measure the SMBH mass, and map the small-scale geometry and kinematics of gas around the SMBH. Dynamical modeling does so by modeling time-series photometric variations and spectroscopic variations of emission-line profiles. Here, I present dynamical modeling results in a highly-variable AGN (RM160, z=0.3593) with SDSS data, varying by nearly a magnitude over its near 15 year photometric light curve. RM160 has displayed large velocity shifts in its broad emission-lines and evidence for a line breathing response to the continuum in Hα, Hβ, MgII. Additionally, all three emission-lines display a lag with the continuum, showing tentative evidence for BLR stratification. Dynamical modeling was performed using these three different emission-lines and three separate time-periods, to probe the gas around the SMBH and its evolution over time. As we find evidence for a lack of viriality in the gas within RM160, I will discuss its effect on the measurement of SMBH mass. I will cross-compare models and discuss the change in geometry and kinematics of the gas across emission-lines/time, and its relation to radiative transport theory. |
10:18 AM | The Nature and Host Galaxies of Changing-Look AGNs in SDSS-V | Grisha Zeltyn |
Novel time-domain surveys, including the SDSS-V, are revolutionizing our understanding of supermassive black hole (SMBH) accretion and AGN variability, revealing dramatic changes in just months to years. In particular, changing-look AGNs (CL-AGNs) show the emergence or disappearance of broad emission lines and quasar-like continua in their UV/optical spectra on unexpectedly short timescales of years and sometimes even months. In this talk, I will present our study of a sample of dimming CL-AGNs identified through the BHM program in SDSS-V, and supported by follow-up high-resolution spectroscopy from the VLT and Gemini observatories. Our analysis provides yet stronger evidence for changes in the accretion flow being the driver for the drastic transitions, and reveals that the host galaxies of CL-AGNs show similarities to those of typical, low-redshift AGNs. I will also demonstrate how this data may allow us to get novel insights into SMBH mass estimators and SMBH-host co-evolution, by comparing the location of CL-AGNs in the M-σ plane with that of other types of (active) galaxies. |
10:30-11:00 AM | Coffee |
11:00-12:45 PM | Session 8 | Chair: Xiang-Xiang Xue |
11:00 AM | The Rich and the Poor in living in downtown Milky Way | Hans-Walter Rix |
The central few kiloparsec of our Galaxy are home to the largest concentration of very metal-poor and extremely metal-rich stars in our Milky Way. The Galactic Genesis program has densely targetted these stars over the last years, including in the inner few degrees where Gaia cannot see. I will show what we are learning from this great new data set. |
11:12 AM | Radial and Azimuthal Galactic Chemical Gradients in SDSS-V with the OCCAM Survey | Jonah Otto |
In the first SDSS-V update of the Open Cluster Chemical Abundances and Mapping (OCCAM) survey, we present over 200 open clusters with data from DR19 observed with the APOGEE instrument, as well as over 150 additional open clusters observed as part of MWM with the BOSS instrument. We leverage this large dataset to update the radial Galactic chemical abundance gradients derived in Myers et al. (2022) and Donor et al. (2020). As well as, for the first time, use the OCCAM open cluster sample to explore the azimuthal variation along bands of constant radius. As part of the vetting process, bulk cluster parameters were computed using Gaia-based membership from both Cantat-Gaudin et al. (2020) and Hunt and Reffert (2024) and the DR19 RVs and metallicities. Additionally, as part of our verification, we compare results from several different Astra analysis pipelines (e.g., ASPCAP, AstroNN), as well as the SDSS-IV DR17 ASPCAP results. |
11:24 AM | Optical Spectroscopy Reveals Hidden Neutron-capture Elemental Abundance Differences among APOGEE-identified Chemical Doppelgangers | Catherine Manea |
Grouping stars by chemical similarity is fundamental to many Galactic studies that leverage stellar abundances to disentangle our Milky Way's evolutionary history and present day structure. The APOGEE stellar spectroscopic survey, with its high resolving power, access to over 20 elemental species, and sensitivity to distant giant stars, is a popular and effective tool for this task. However, APOGEE notably lacks access to strong lines of the neutron-capture elements (Z>30), which have been shown to behave distinctly from the lighter elements. We assess whether APOGEE abundances are sufficient for identifying chemically similar disk stars by identifying 25 pairs of chemical "doppelgangers" in APOGEE DR17 and following them up with the Tull spectrograph, an optical R~60,000 echelle instrument on the 2.7m telescope at McDonald Observatory. Line-by-line differential analysis of each pair's optical spectra reveal detectable differences (Δ[X/Fe] ~ 0.03-0.15 dex) in neutron-capture element (Y, Zr, Ba, La, Ce, Nd, and Eu), Cu, Zn, and/or Na abundance ratios in 20/25 pairs despite sharing nearly identical APOGEE-reported abundances and C/N ratios, a tracer of giant star age. We find correlations between doppelgangers' similarity in neutron-capture abundance ratios and their similarity in orbital parameters such as R_guide and vertical action. We illustrate that optically-measured neutron-capture elements improve the search for stars with similar compositions and Galactic origins, even when APOGEE abundances derived from SNR>300 spectra are available. These results hold implications for the chemical dimensionality of the disk, mixing within the interstellar medium, and chemical tagging with the neutron-capture elements. |
11:36 AM | The chemical evolution modes of our Galaxy using MWM DR19 data | Szabolcs Mészáros |
We calculated new GCE models simulating the chemical evolution of the Milky Way as constrained by a golden sample of 394,000 stellar abundances of the Milky Way Mapper survey from the 19th data release of SDSS-V. The separation between the chemical thin and thick disks is defined using [Mg/M]. We use the chemical evolution environment OMEGA+, combined with Levenberg-Marquardt and bootstrapping algorithms for optimization and error estimation. We simulate the entire Galactic disk and consider six galactocentric regions, allowing for a more detailed analysis of the formation of the inner, middle, and outer Galaxy. We investigate the evolution of α, odd Z, and iron-peak elements: 15 species altogether. Our results show a well-defined peak in the rate of the infalling matter as a function of the Galactic age, confirming a merger event about 10 Gyr ago, also proposed by previous studies. |
11:48 AM | Leveraging Stellar Kinematics to Cross-Calibrate Gyrochronology and [C/N] Ages | Lucy Lu |
Determining stellar ages is challenging, as age is strongly dependent on other stellar parameters and often requires an underlying stellar evolution model. This complexity increases when comparing different age-dating methods, as they rely on distinct indicators and are often applicable to non-overlapping regions of the color-magnitude diagram. Fortunately, the age-velocity-dispersion relation (AVR) is a universal feature among stars of all evolutionary stages. In this talk, I will explore the potential for cross-calibrating [C/N] and gyrochronology ages using stellar kinematics, anchoring on asteroseismic ages determined in APOKASC-3. |
12:00 PM | Testing Gyrochronology in Old Low Mass Stars | Amanda Ash |
One of the most glaring weaknesses in stellar rotation models is that we must extrapolate patterns calibrated in young high mass stars to domains with little data, such as old or low mass stars. Kinematic ages, which use a star’s vertical velocity dispersion as a proxy for age, provide an exciting new avenue for stress-testing these underlying assumptions with larger samples and older stars than previously attainable. A promising place to test the models is to allow the field topology to evolve with time, which could change the predicted torque evolution, and we test models incorporating this additional degree of freedom. Using rotationally converged stars in open cluster and kinematic data we determine the best fit gyrochronology parameters as a function of age. We find marginal evidence of time-evolution in the efficiency of the stellar spin down. We then project this constrained model to the gyro-kinematic data and the unconverged M dwarf sample. In cases where our model fails to reproduce properties seen in the larger kinematic sample, we determine whether adjustments within the model’s current framework including the saturation threshold and the field topology can bring the model into agreement with observed rotation periods. This allows us to determine the whether the underlying physical assumptions of the model are realistic, or if a new physical model should be adopted. Finally, we compare starspot filling factors, measured using APOGEE spectra, to determine whether the rotation model makes reasonable predictions for the magnetic field strength of the star. |
12:12 PM | MWM 101 | Jon Bird |
12:30-1:30pm | Lunch |
1:30-2.30 PM | Individual Mappers discussion | Mappers’ heads |
2:30 PM | Transportation |
2:30-7.00 PM | Flexible afternoon |
7:00pm | Public Talk | Haus der Astronomie |
Heiße Sterne, Schockwellen und riesige Blasen: Eine neue Erforschung der Milchstraße und der Magellanschen Wolken | Tom Herbst & Niv Drory |
Dieser öffentliche Vortrag begleitet die Tagung des internationalen wissenschaftlichen Konsortiums, das die Himmelsdurchmusterung "Sloan Digital Sky Survey" (SDSS) organisiert. Im Mittelpunkt steht ein neues Observatorium, das als Teil des SDSS in Chile gebaut wurde, um die Bewegung von Gas in der Milchstraße aufzuzeichnen. Sowohl das MPIA als auch die Universität Heidelberg haben bei der Entwicklung dieses Observatoriums Beiträge von zentraler Bedeutung geleistet. Heiße Sterne spielen eine wichtige Rolle bei der Entstehung und Entwicklung von Galaxien, indem sie Gas auseinander treiben und die Bildung neuer Sterne verlangsamen. Dieser Prozess kann mit dem neuen „Local Volume Mapper“ (LVM) Observatorium in Chile, der 2023 in Betrieb genommen wurde, noch genauer beobachtet werden. Der LVM kartiert die riesigen Blasen und Schockwellen, die von heißen Sternen in unserer Milchstraße und ihren Satellitengalaxien erzeugt werden. Der Vortrag erklärt die ersten wissenschaftlichen Ergebnisse des Projekts und stellt gleichzeitig die Instrumente vor, die in Heidelberg für den „Local Volume Mapper“ entwickelt und konstruiert wurden. Tom Herbst ist Astronom am MPIA und Teleskopwissenschaftler für den „Local Volume Mapper“, Niv Drory ist Leiter des „Local Volume Mapper“-Programms und arbeitet an der Universität von Texas. |
Thursday June 5th 2025 |
8:30 AM | Transportation |
9:00-10:30 AM | Session 9 | Chair: Andrew Saydjari |
9:00 AM | MWM 101: Solar Neighborhood Census | Ilija Medan |
In SDSS-V, the Solar Neighborhood Census (SNC) is targeting a volume limited sample of stars with the goal of cataloging a representative sample across the main sequence. While the resulting sample will not be volume complete, the data from SDSS-V will facilitate a much better understanding of the stellar population of the Solar Neighborhood. By combining these spectra with photometric and astrometric data, we can fully characterize the physical properties of the volume’s varied constituents. This includes, determining accurate stellar parameters like temperature, mass and metallicity; identifying binary systems, young stars and rare halo objects; and characterizing the local white dwarf population. When these data are combined with a well defined selection function, we can constrain the Milky Way's initial mass function, multiplicity fraction and star formation history as a function of chemistry and age. In this 101 talk, I will outline which SDSS-V data products will facilitate these advancements, demonstrate how we plan on using these data throughout the survey and highlight some early science results from the working group. These results are crucial in our efforts to fully understand a representative population of stars in the Milky Way and we are excited that the data from SDSS-V will extend our understanding of the Solar Neighborhood from its highest to lowest masses. |
9:30 AM | Oddities in the SDSS-V DR19 White Dwarf Catalog | JJ Hermes |
With spectroscopy from SDSS-V of more than 20,000 white dwarfs, we have uncovered a number of rare and interesting phenomena in the dataset. I will discuss some of these spectroscopic oddities, including the scars of disrupted exoplanets, strongly magnetic stellar remnants, and interesting binaries. |
9:42 AM | Characterizing Low-Mass Dwarfs with Alpha Hulling Standardization | Zach Way |
SDSS-V has observed more than 330,000 low-mass stars (M_G > 8) with BOSS with over 500,000 unique visits. There are many different methods of analyzing these spectra (MDwarfType, the SLAM, LASPM) but each has a common problem in accounting for spurious instrumental effects, low signal-to-noise, issues in spectrophotometry, and lack of robust continuum normalization. Alpha Hulling Standardization (Medan et al., in prep) is a new method to standardize the spectra of M dwarfs that can account for large changes in the SED of the spectrum due to astrophysical and instrumental effects and is independent of SNR. This method differs from traditional normalization methods in that it does not search for a physical continuum, but instead finds the optimal pseudo-continuum that preserves the broad molecular features that encode the star’s fundamental parameters. This method lends itself to statistical and machine-learning methods. We show that a simple weighted principal component analysis (wPCA) of the standardized spectra successfully identifies atypical spectra (e.g. M dwarf/white dwarf binaries) or special features (e.g. activity indicators). We also investigate whether these standardized spectra can be used to identify unresolved binaries; this is accomplished by training a simple Random Forest Regressor model to predict a star’s location on the Gaia CMD based on the wPCA eigenvalues, so overluminous binary systems can be easily identified. This work demonstrates that, with properly standardized spectra, we can fully utilize the SDSS-V data to better understand the large population of M dwarfs that will be observed. |
9:54 AM | The kinematics of young massive stars in the Milky Way disc: first results from SDSS-V | Eleonora Zari |
SDSS-V is surveying an unprecedented sample of ~500 000 hot stars in the Milky Way, and obtaining multi-epoch low-resolution BOSS spectra. While the survey coverage of the Galactic plane is not yet complete, the amount of data collected so far allows for a first inspection of the kinematic properties of the sample. We employ the spectral parameters (Teff, logg) and line-of-sight velocities derived by the BOSS Net method to select stars hotter than 12,000 K and to compute their 3D velocities and actions (by combining with Gaia DR3 astrometric information). We find strong radial motions with respect to the Galactic centre, alternating inward/outward, and coherent over several kpc's. The inward motions are loosely associated with the underlying spatial density distribution of hot massive stars, which suggests a relation with the spiral arm pattern. We discuss this result in the context of current theoretical models of the Milky Way spiral structure and by comparing with numerical simulations. |
10:06 AM | Studying Star Formation in Different Environments Across the Milky Way with SDSS-V | Mojgan Aghakhanloo |
Understanding star formation demands an approach that examines both the intrinsic properties and the dynamic states of young stars. In this talk, we present our planned investigation of 13 Galactic protoclusters probing different Galactic environments using BOSS and APOGEE spectra combined with Gaia astrometry. We target all bright stars (G < 16) within a 35-arcminute radius of these gas-dominated, actively star-forming regions, acquiring spectra for over 53,000 sources. Our primary goal is to identify Young Stellar Objects by detecting their distinctive spectral signatures, which serve as vital tracers of early stellar evolution. Once these YSOs are identified, we will derive fundamental stellar parameters, such as effective temperatures, masses, and radial velocities, and will confirm cluster membership to better assess the dynamics of these protoclusters. Furthermore, by integrating SDSS-V and Gaia data, we will analyze stellar motions to determine contraction and expansion rates and reveal kinematic substructures that illuminate the formation history and dynamical evolution of these early-stage clusters. Studying these protoclusters using SDSS-V data promises to enhance our understanding of the physical conditions governing star formation and the evolutionary processes shaping stellar populations in diverse Galactic environments. |
10:18 AM | First BOSS look at SDSS-V OBA stars | Jaime Villaseñor |
SDSS-V is on track to assemble an exceptionally large sample of massive stars. The upcoming Data Release 19 (DR19) will feature thousands of OB stars and even more A-type stars, providing an unparalleled opportunity to probe their physical parameters and exploit the survey’s multi-epoch design. Among the survey’s most compelling goals is the search for black-hole companions in massive stars, a challenge that has yielded only a handful of detections to date. Unlike previous spectroscopic efforts, which typically target a few hundred objects, SDSS-V will significantly increase the chances of revealing these elusive systems. In this presentation, I will give an overview of the massive stellar content in DR19 and discuss our first high-resolution follow-up campaign with FEROS in the southern hemisphere, designed to identify promising black-hole candidates among SDSS-V’s high radial velocity variables. |
10:30-11:00 AM | Coffee |
11:00-12:30 PM | Session 10 | Chair: J. Villaseñor |
11:00 AM | Mapping the Distant and Metal-Poor Milky Way with SDSS-V | Vedant Chandra (Remote) |
SDSS-V will observe the largest all-sky spectroscopic dataset of stars in the Milky Way's stellar halo. This is enabled by novel selection strategies to identify the most distant and most metal-poor stars in the Galaxy. In these distant and metal-poor extremes, it is vital to incorporate all available information about a star when deriving its fundamental parameters. I will describe the stellar parameter pipeline for the SDSS-V halo survey, which is available to the collaboration as a value-added catalog. Our results are validated with dedicated observations of star clusters, and a comparison to high-resolution APOGEE data. I will showcase the scientific capabilities of this dataset, from identifying chemically peculiar stars to providing an all-sky inventory of halo substructure. |
11:12 PM | LAMPS: high-resolution spectroscopic followup of Low-Alpha Metal-Poor Stars in SDSS-V | Alex Ji |
The Milky Way's stellar halo forms largely from the accretion and tidal disruption of dwarf galaxies. Gaia and spectroscopic surveys like APOGEE have enabled the discovery and characterization of the more massive accreted dwarf galaxies, with stellar masses above ~10^7 Msun. However, the lower mass dwarf galaxies are more numerous and harder to identify. Fortunately, stars from these low-mass galaxies have a unique chemical tag: they are Low-Alpha ([a/Fe] < 0.2) and Metal-Poor ([Fe/H] < -1.5) Stars. These LAMPS can be identified in SDSS-V from both high-resolution APOGEE and low-resolution BOSS spectroscopy. I will present early results from high-resolution optical spectroscopy of LAMPS, revealing stars associated with dwarf galaxies across a range of stellar masses and stars exhibiting signatures of iron-rich supernovae. These findings provide new insights into the chemical evolution and assembly history of the Milky Way. |
11:24 AM | Constraining Massive Star Multiplicity in SDSS-V with Few-Epoch Spectroscopy | Johanna Müller-Horn |
Binary interactions shape the evolution of massive stars, making their multiplicity properties essential to understand. In particular, the period distribution determines whether and when binaries interact, influencing their evolutionary pathways and outcomes. SDSS-V’s extensive spectroscopic dataset of thousands of Galactic OBA stars provides a unique opportunity to study massive star multiplicity. However, its limited epoch coverage (~3 spectra per star) poses a challenge, as >~10 epochs are typically required to determine individual orbital parameters. We present a new statistical framework to infer key multiplicity properties—binary fraction, period, eccentricity, and mass ratio distributions—even in the few-epoch regime. Instead of determining orbital solutions for individual stars, it provides probabilistic constraints on population properties, and we show how it can be applied to exploit the SDSS-V dataset. |
11:36 AM | Untangling binary stars with APOGEE spectra | Rhys Seeburger |
SDSS-IV and V have accumulated more than 50,000 single- and multi-epoch APOGEE spectra for over 30,000 stars where Gaia has spectroscopic or astrometric evidence of binarity. We use APOGEE to search for signs of two luminous components, and try to estimate their relative fluxes, and in a few cases masses. This information breaks modelling degeneracies that beset the Gaia information. I will show first results of some interesting and unusual systems. |
11:48 AM | Chemical Variations in SDSS-V Milky Way Mapper Open Cluster Close Binaries | Amaya Sinha |
Most stars form in binaries, as a result it’s important to understand the impact of multiplicity on abundances and evolution. Using SDSS-V DR19 radial velocities and spectra we seek to measure the impact that close binarity has on surface chemistry across the HR diagram in a broad set of abundances. To accomplish this we leverage the assumptions of chemical homogeneity in open clusters, and compare the surface abundances of SB1s to non-binary stars at similar evolutionary states. We determine binarity by analyzing DR19 open clusters with The Joker, and we derive abundances from DR19 spectra using BACCHUS. We constrain the median abundances, as well as the intrinsic scatter, within the binary and nonbinary populations in each cluster, and find that binary populations in open clusters are potentially enriched in carbon and cerium as compared to their non-binary counterparts. Finally, we measure a potential connection between abundance enrichment and separation, that could be indicative of past mass transfer. |
12:00 AM | Unveiling the Magellanic Clouds with the SDSS-V Magellanic Genesis Survey | David Nidever |
The Magellanic Genesis survey (part of MWM) is creating a contiguous map of the LMC and SMC using the southern APOGEE and BOSS spectrographs. The APOGEE portion is observing ~20,000 bright AGB stars in the central regions, while over 100,000 fainter RGB stars extending to a radius of 20 kpc (20 deg) are being observed with BOSS. The combination will provide the first contiguous kinematical and chemical maps of the MCs that will unveil both their evolution of the individual galaxies and their mutual interactions. A substantial fraction of the planned targets have already been observed. I will present an overview of the survey and highlight some initial science results. |
12:12 PM | Mapping Chemical ISM Variation with APOGEE Diffuse Interstellar Bands | Andrew Saydjari |
After modeling out the star’s contribution, residuals in stellar spectra are replete with features that correlate with dust, known as diffuse interstellar bands (DIBs). These features arise from molecules in the interstellar medium (ISM) related to formation and destruction processes of dust grains and thus provide a unique chemical window into dust composition. Using all-sky, NIR, APOGEE spectra that penetrate significant dust column densities, we can leverage these DIBs to map chemical variations in the ISM on a grand scale. First, we will show that scatter in the correlation between DIB strength and dust column is at least partially explained by variations in the global slope of the dust extinction curve, attributed to changes in the dust grain size distribution or fraction of polyaromatic hydrocarbons (PAHs). This provides some of the most compelling evidence to date that DIBs trace real differences in the ISM that reflect compositional changes. Then, we will demonstrate how DIBs can be used to investigate the chemical changes accompanying variations in the Galactic environment (e.g. UV radiation field). We will review the power of DIBs as probes of ISM chemistry and present new evidence on the relationship of these features over a broad range of spectral sizes (widths in wavelength). |
12:24 PM | Tomographic Distance Measurements of HVCs with SDSS-V Milky Way Mapper | Timothy McQuaid |
The Smith Cloud, a prominent high-velocity cloud (HVC), serves as a key laboratory for studying cold gas accretion and its role in sustaining star formation in the galaxy. Accurate measurements of HVC distances are essential for determining their mass and accretion rates, which are crucial for fully understanding the impact of HVCs on the evolution of the Milky Way. The only direct method to measure these distances involves detecting absorption lines (e.g., Na I and Ca II) in the spectra of stars with known distances at the velocity of the HVC. However, this approach typically requires time-intensive surveys that can only obtain a limited number of stars covering a HVC with sufficient spectral resolution. For example, the Smith Cloud’s currently accepted distance of 12 kpc is highly uncertain, relying on a single detection of Ca II absorption. We therefore leverage the extensive dataset of optical spectra from the Sloan Digital Sky Survey-V (SDSS-V) Milky Way Mapper program, which has obtained spectra for over two million stars across the sky and several thousand covering the Smith Cloud, alongside precise distance measurements from Gaia. By fitting stellar models to these spectra, we isolate the residual Na I and Ca II absorption associated with the interstellar medium and HVCs, as well as measure stellar extinction. This approach enables a tomographic analysis to accurately map the distances to HVCs such as the Smith Cloud. Our analysis reveals an onset of both Ca II absorption and reddening at 5 kpc towards the Smith Cloud, indicating a significantly revised, closer distance estimate to the HVC. |
12:30-1:30 PM | Lunch | |
1.30-2.00 PM | Full Dome Visualization Chat |
2:00-3:30 PM | Splinter Session 1: The Halo | Room TBD |
2:00 PM | Fossils in our backyard: the MWM local halo survey | Sébastien Lépine |
As part of the Milky Way Mapper survey, we have been systematically targeting stars with estimated transverse motions VT > 150 km/s. We have already collected spectra for more than 300,000 relatively nearby (d < 2 kpc) high-velocity stars from this sample, the majority of which consists of low-mass K and M stars observed with BOSS, but also includes larger numbers of main-sequence turnoff stars, subgiants and blue stragglers, and more than 1,500 high-velocity white dwarfs. I will review the reach and contents of this survey of the local galactic old-disk and halo population, with a focus on their 3D kinematics and metallicity distribution and possible applications. |
2:12 PM | StarHorse stellar parameters, distances, and extinctions for stars with APOGEE DR19 spectra: Exploration of the Galactic Bulge (Remote) | Samir Nepal |
We combine high-resolution spectroscopic data from SDSS-V DR-19 APOGEE spectroscopy with broad-band photometric data from several sources as well as parallaxes from Gaia Data Release 3 (DR3). Using the Bayesian isochrone-fitting code StarHorse, we derived distances, extinctions, and astrophysical parameters for all APOGEE stars. We performed full orbit integrations considering a barred galactic potential and employed detailed orbital frequency analysis to identify the galactic components. Using the new StarHorse for APOGEE DR-19 run, we will present our exploration of the galactic bulge to present new results. Our results provide strong constraints on the galactic bulge formation mechanisms. |
2:24 PM | Discussion Session | Vedant Chandra and Alex Ji |
2:00-3:30 PM | Splinter Session 1: Reliability of AGB Spectral Decomposition and BH Masses | Room TBD |
2:00 PM | Discussion Session | Lead By: Johannes Buchner and Amy Rankine |
2:00-3:30 PM | Splinter Session 1: LVM Talk Session I | Room TBD |
2:00 PM | The multiscale properties on resolved IFS data: using the LMC as an astrophysical laboratory using one million spectra | Hector Ibarra-Medel |
We aim to analyze the complete set of LMC tiles to generate a set of data cubes at multiple scales, from which we will examine the stellar population properties, gas and stellar dynamics, and chemical abundances from 5 pc up to 1 kpc. We will generate a set of data cubes with the nine dithering patterns, run the co-added spectra with the DAP and pyPipe3D, and generate a set of SSP and gas maps resulting from the DAP and pyPipe3D. This project also proposes a future LVM-VAC with the data cubes, DAP, and pyPipe3D outputs. |
2:12 PM | Benchmarking Integrated Light Studies of Stellar Populations: Early Science Observations of Omega Centauri with the LVM | Maximilian Häberle |
With its wide field of view, the Local Volume Mapper (LVM) provides a unique tool to capture a large part of the light of even the closest Milky Way globular clusters in a single observation. Due to the large spaxel size, it is not able to resolve single stars, but instead measures the integrated light of the clusters. The spectral resolution of R=4000 allows to study various properties of the clusters, including the age and metallicity of their stellar populations and their kinematic properties. The spatial resolution for globular clusters in the Milky Way is on the order of around 1 parsec per spaxel, comparable to what can be achieved with high-resolution studies of extragalactic star clusters e.g. in M31. Therefore, the LVM data provides the opportunity to test our methods for extragalactic population studies with well-known local objects. In this talk I will present preliminary results based on early science observations of the massive globular cluster Omega Centauri. With its complex stellar populations, which have been studied in detail using resolved observations of thousands of individual stars, it provides the ideal target for testing methods used for integrated light studies. |
2:24 PM | Mapping the physical and chemical properties of the Galactic WR nebulae with SDSS-V/LVM | Oleg Egorov |
Wolf-Rayet (WR) stars exhibit powerful winds that can create prominent, expanding bubbles enriched by stellar nucleosynthesis products, which then mix with the surrounding interstellar medium (ISM). Spectral studies of extragalactic HII regions containing WR stars, as well as the brightest small-scale regions of Galactic WR nebulae, have revealed an overabundance of nitrogen, helium, and other elements. However, a detailed characterization of the resolved 2D structure of the physical and chemical properties across WR nebulae is still lacking. Two well-known Galactic WR stars (WR6 and WR18) and their surrounding ring nebulae were observed by the SDSS-V Local Volume Mapper IFU. I will present the results on the gas kinematics, ionization, temperature, and chemical structure of these WR bubbles and their surroundings at sub-parsec resolution. Our findings indicate that these WR nebulae are mostly chemically homogeneous, with a clear overabundance of certain elements compared to their surroundings. At the same time, the temperature structure reveals prominent regions of hot gas leaking from the bubbles, consistent with earlier X-ray observations by eROSITA and Chandra. |
2:36 PM | A multiscale analysis of the stellar properties and kinematics in the Magellanic Clouds using SDSS-V LVM data. | Rodolfo de J. Zermeño-Padilla |
Taking advantage of the wide-angular-scale spectroscopy data provided by SDSS-V LVM, we will analyze the stellar population metallicities and ages, along with the gas and stellar kinematics of the Magellanic Clouds at different spatial scales. We hope that our results can improve our interpretation of extragalactic object observations, and bring additional detail about the interaction between the stellar disk and ionized medium, shedding light of both MC's recent history. |
2:48 PM | The LMC-N44 region: LVM and MUSE observations compared | Tony Wong |
We have compiled multiple LVM exposures towards the N44 HII region in the LMC and generated an improved mosaic from previously published MUSE observations of the central N44 region. These IFU observations probe stellar feedback in action, with multiple O stars, HII regions, bubbles, and supernova remnants present. We provide a brief status report on how these datasets compare and complement one another. |
3:00 PM | Discovery of ~2200 new supernova remnants in 19 nearby star-forming galaxies with MUSE spectroscopy and quantifying their influence on H II region metallicity | Jing Li |
Supernova remnants (SNRs) play a crucial role in the energy and chemical feedback cycle of galaxies, yet their direct impact on the surrounding interstellar medium (ISM) remains poorly understood. Using optically integral field spectroscopy from the PHANGS–MUSE survey, we construct the largest extragalactic SNR catalog to date, identifying ~2,200 SNR candidates across 19 nearby star-forming galaxies. Our identification is based on multiple optical diagnostics, including [S II]/Hα and [O I]/Hα line ratios, velocity dispersion maps, and Baldwin–Phillips–Terlevich (BPT) diagrams. To evaluate the influence of SNRs on chemical enrichment, we analyze gas-phase abundances in H II regions at varying distances from SNRs. Surprisingly, we find no statistically significant differences in metallicity, suggesting either supernova ejecta have not travelled so far or dilution of metal-enriched gas below detectable levels. These results have important implications for our understanding of metal transport in galactic disks and the timescales over which local enrichment becomes observable. Looking ahead, the SDSS-V Local Volume Mapper (LVM) will provide an unprecedented opportunity to extend this work by conducting spatially resolved spectroscopic mapping of the ISM in nearby galaxies. With its capability to obtain optical spectra at sub-kiloparsec resolution over wide fields of view, LVM will allow us to systematically probe the interplay between SNR-driven feedback and chemical enrichment across different galactic environments. By integrating LVM observations with our existing PHANGS–MUSE dataset, we aim to refine models of ISM metal mixing and feedback efficiency, bridging the gap between small-scale resolved studies and global galactic evolution. Our findings highlight the importance of large-scale, multi-wavelength spectroscopic surveys like SDSS-V/LVM in constraining the impact of stellar feedback processes and advancing our understanding of galaxy evolution across cosmic time. |
3:12 PM | AMASE-P: A Complementary Instrument and Survey to LVM | Renbin Yan |
We are building a cost-effective, fiber-based, integral field spectrograph with similar angular resolution and coverage as LVM but have a high spectral resolution of R~15,000. It is a prototype to a future large array of spectrographs that will be called the Affordable Multiple Apeture Spectroscopy Explorer (AMASE). The prototype spectrographs are called AMASE-P and will make up two observing systems located on the northern and southern hemispheres. The northern observing system is funded by Hong Kong Jockey Club Charities Trust and will be called the Jockey Club Spectroscopy Survey System (JCS3). It will consists of a 0.8m telescope and a Canon telephoto lens, both of which can feed three hexagonal 547-fiber bundles. Each bundle will feed one spectrograph. The southern system will include just a Canon telephoto lens, two fiber bundles, and two spectrographs. The system is very complementary to LVM as our high spectral resolution enables us to resolve different velocity components, measure kinematic temperature, and probe turbulence at a level of several km/s in the ISM of the Milky Way and nearby galaxies. We plan to survey a few hundred square degrees of sky and could potentially have significant overlap with LVM to maximize science output from both surveys. |
2:00-3:30 PM | Splinter Session 1: EPO Hack Session | Room TBD |
2:00 PM | Discussion Session | Niall Deacon |
3:30-4:00 PM | Coffee |
4:00-5:00 PM | Splinter Session 2: Young Stellar Objects | Room TBD |
4:00 PM | Open questions in star formation and potential answers from SDSS | Jonathan Tan |
I discuss several open questions in star formation and how analysis of SDSS data can help answer them. In particular, I focus on the spatial and kinematic clustering of star formation activity and how SDSS observations of young stellar objects allow us to determine the dynamical state of young clusters and associations and the mechanisms that may be responsible for triggering their birth. |
4:12 PM | Supervised Machine Learning Algorithms for Stellar Clustering in the Sco-Cen Complex | Elena D'Onghia |
The formation and early evolution of stars remain open questions in astrophysics. While stars typically form in clusters, many older stars are observed in isolation, suggesting that stellar feedback mechanisms—such as supernovae and stellar winds—disrupt their original groups and alter their kinematics. However, the precise processes driving this evolution remain poorly understood. In this study, we apply advanced machine learning-based clustering algorithms—HDBSCAN, SSN, and SigMA—to identify co-natal stellar populations. First, we test these algorithms on the FIRE simulations to assess their effectiveness in recovering groups of stars with shared origins. We then apply them to the Sco-Cen star-forming region using Gaia and SDSS-IV/V data to reconstruct its star formation history. Our approach promises to reveal key insights into the clustering and dispersal of young stars, offering a new perspective on the dynamics of stellar formation and feedback processes. |
4:30 PM | Discussion Session | Eleonara Zari and Jaime Villasenor |
4:00-5:00 PM | Splinter Session 2: BHM & eROSITA Talk Session | Room TBD Tom Dwelly |
4:00 PM | Towards a volume-limited sample of accreting compact binaries (Remote) | Jaco Brink |
The eROSITA all-sky surveys have uncovered about three million new X-ray sources. Accreting compact binaries (ACBs) form a small but important sub-sample of these sources. By incorporating machine learning techniques, we have identified roughly 11,000 potential ACB candidates in the eROSITA data sample. Optical spectroscopic observations are, however, now required to determine whether these candidates are true ACBs. For this project we are, therefore, conducting follow-up optical spectroscopic observations of these candidate systems using various instruments across the world, including SDSS, ESO and SAAO facilities. However, identification spectra are not enough to determine the probable subclass of ACBs. Therefore, following the positive identification of an ACB, time-resolved photometric observations are obtained, primarily using the SPECULOOS-south and STELLA telescopes, to determine the orbital periods of these systems, which would enable further sub-classification. The primary goal of these observations is to obtain a complete 150pc volume-limited sample of all ACBs, after which we intend to extend to a 500pc complete sample. Having these complete volume-limited samples will enable us to better understand the evolution of close binary systems, as well as constrain the contribution of ACBs to the total high-energy output of the Galaxy. All of these observations are ongoing, and has already yielded around 160 new ACB systems. In this talk I will give an overview of these observations, talk about some of the results, and discuss the future prospects of this project. |
4:12 PM | The X-ray properties of the eROSITA-selected SDSS-V quasar sample | Amy Rankine |
Quasar winds are potentially capable of expelling large quantities of gas from their host galaxies and may thus be an important mechanism for feedback. These winds are evident in rest-frame UV spectra in the form of blueshifted broad emission lines and broad absorption lines. How such winds are launched – and how such launching relates to the physical state of the accretion disc system that powers quasars – remains a key open question. SDSS-V follow-up of eROSITA sources is yielding a large quasar sample for which we have access to their wind properties and (via measurements of the X-ray, UV and optical emission) constraints on their accretion state. I will present new measurements for a sample of redshift 1.5-3.5 quasars that quantify how the strength of quasar winds (from the CIV emission line and broad absorption lines) depends on both the strength of the UV ionising continuum (probed via HeII emission) and the X-ray properties derived from the eROSITA spectra (i.e., photon index and N_H column density). We show that quasars with a given X-ray luminosity have a broad range of wind properties that appear to depend on the presence (or lack) of a strong, UV-bright inner accretion disc (revealed by the HeII emission line strength). With this information in hand we can investigate what, if any, X-ray conditions are required for driving winds and gain a new perspective of the wind properties of the X-ray selected quasars. |
4:24 PM | From Quasar Spectra to Structure: SDSS-V Quasar Spectral Analysis and AGN Photoionization Studies | Qiaoya Wu (Remote) |
The large-scale, deep-field quasar spectroscopy from SDSS-V provides a unique opportunity to investigate AGN emission-line properties and the physical conditions of their line-emitting regions. In this talk, I will present our latest analysis of SDSS-V and DESI DR1 quasar spectra, highlighting the emission-line characteristics and quasar demographics. These datasets enable a more comprehensive exploration of AGN properties across different redshifts and luminosities, shedding light on black hole growth and evolution. Beyond statistical analyses, I will demonstrate that our photoionization modeling of the broad-line region can provide insights into mapping the unobservable ionizing continuum. By combining observational constraints with physically motivated models, we aim to refine our understanding of AGN accretion physics and line-emitting regions. |
4:36 PM | SDSS IV and V Quasars Intermediate Redshift Black Hole Mass Estimates with 10 year multi-epoch observations | Raquel Baza-Medina (Remote) |
This work presents the results of spectroscopic multiple-epoch observations of five selected quasars; using spectroscopic optical observations with Hꞵ emission line. The quasars are selected from the BHM Survey from the SDSS-IV and SDSS-V projects; with redshift between 0.2 < z < 0.8 given a total of approximately 133 spectra per object. The final objects are the following: RM17 with a signal-to-noise ratio of SNR ~ 59.24, RM160 with SNR ~ 24.16, RM272 with SNR ~ 31.36, RM101 with SNR ~ 83.28, and RM320 with SNR ~ 44.74. The observations were carried out on average between 2013-2023, given about 10 years of observations. This quasar sample was processed through the code MESFit or Multi-Epoch Spectral Fitting to perform the spectral decomposition of AGN in time-series analysis (Guo et al. 2018, Shen et al. 2019) showing the spectra with an important variability for the Hꞵ line across different observation epochs, this line is particularly important for its subsequent use in the Reverberation Mapping Technique (RM) as an important way to obtain the Broad Line Region (BLR) size and, consequently, the Super Massive Black Hole (SMBH) masses of the quasar sample. The same information is used to obtain the masses with another method; this method is the luminosity-mass relation proposed in Vestergaard et al. (2006), with the purpose of comparing both the RM technique and the luminosity-mass relation. Using the RM method time delay calculated, through JAVELIN (Just Another Vehicle for Estimating Lags In Nuclei) (Zu et al. 2013). Future work includes work with the Ha broad line, where RM studies have shown difficulties in the literature and we will consider incorporating the most recent results from SDSS-V. |
4:48 PM | Spectral Variability in the Extreme Populations of the Quasar Main Sequence | Daniel Serrano (Remote) |
Quasars exhibit significant variability in brightness over timescales from days to years across the electromagnetic spectrum. This variability is linked to central region dynamics, affecting both luminosity and the broad-line region (BLR), leading to spectral changes (Peterson & Bradley 1997). In 1992, Boroson & Green identified an anticorrelation between Fe II and [O III] emission and the H_β line width, known as Eigenvector 1 (EV1). This relationship is driven by quasar physical properties rather than orientation. Subsequent studies reinforced this, establishing EV1 as an analog to the H-R diagram for quasars (Sulentic et al. 2002). EV1 also enabled a classification: Population A quasars, with strong Fe II emission and high Eddington ratios, and Population B quasars, lacking Fe II emission and exhibiting broad, low-ionization lines. This study builds upon previous work from summer 2023, where six quasars from these extreme populations were selected. PyQSOFIT (Guo, Shen & Wang 2018) was used for spectral fitting, assessing five-year spectral variability and tracking their displacement within EV1. The goal is to analyze spectral variability in these populations to identify significant differences. We will use data from the Reverberation Mapping (RM) project of SDSS-V (5–10 years) and high-cadence photometric data from the COLIBRI telescope to probe shorter timescales. This approach allows a comprehensive analysis: COLIBRI for days, RM for years. RM objects from extreme populations will be selected, followed by spectral fitting with PyQSOFIT. This will provide variability trends, black hole mass estimates (Grier et al. 2017), and insights into quasar physics. We expect the variability in extreme Population B to be significantly greater than that observed in Population A. If confirmed, this would provide valuable insights into the physical differences driving this discrepancy between quasar populations. |
4:00-5:00 PM | Splinter Session 2: LVM Talk Session II | Room TBD |
4:24 PM | Multiscale Physico-Chemical Analysis of the Magellanic Clouds | Lesly Corina Castañeda Carlos (Remote) |
We will analyze the physical conditions (density, temperature, ionization) and chemical abundances of the ionized gas of the Magellanic Clouds observed by the LVM at different spatial scales, considering the impact of stellar populations on these parameters. By creating data cubes with a maximum spectral resolution of 4 pc, we will examine the nebular emission spectra of the LMC and SMC pixel by pixel, assessing their environmental properties. Subsequently, we will degrade the resolution to 8, 17, 34, 68 pc, 2.18 kpc, and ultimately integrate the spectra entirely, mimicking the observation of more distant extragalactic systems. This approach will allow us to analyze the biases introduced by blending regions with different physical and metallicity conditions and the controlled addition of Diffuse Ionized Gas (DIG). |
4:24 PM | Probing SMC Star Clusters with LVM: A Comparison of Integrated Spectra and CMD-Derived Parameters | Saroon Sasi (Remote) |
The VISCACHA survey explores star clusters in the outer regions of the Small Magellanic Cloud (SMC). Expanding on this, our follow-up project aims to study clusters located within the SMC’s main body, leveraging the capabilities of the Local Volume Mapper (LVM) in SDSS-V. LVM’s integral-field spectroscopy provides integrated spectra with a spatial resolution of 10 pc for the Magellanic Clouds, ideally suited for characterizing SMC clusters whose core radii are smaller than a single spaxel. This enables us to derive key parameters, including radial velocities (RVs), ages, and metallicities, from integrated light. As a first step we are using the tiles observed so far with LVM in the SMC, which overlap with several clusters that are analysed by VISCACHA, to derive the aforementioned parameters and compare them with results from CMDs and stellar spectra. We expect to determine RVs with accuracies of 5–10 km/s, while ages and metallicities will be derived by fitting the spectra to stellar population synthesis models. This combination of integrated spectra and photometry from VISCACHAenables a more detailed analysis of star clusters in the SMC main body, offering new insights into their formation, evolution, and role in the galaxy's chemical enrichment history and dynamical evolution. |
4:24 PM | Assessing the ionizing flux of massive star models with spatially-resolved observations of LVM and photoionization models | Oskar Aranguré (Remote) |
The modeling of the ionizing spectra of massive stars is crucial to study the physical and chemical properties of HII regions and star-forming galaxies. However, it is not possible to directly detect the exact shapes and intensities of their spectral energy distributions (SED) beyond the Lyman limit. In this talk, I’ll compare the modeled ionizing flux (Q0) of a potentially single O3 V star with the inferred value from H-alpha luminosity of the surrounding HII region with SDSS-V Local Volume Mapper (LVM) data. I will also detail how we modeled the spatially-resolved LVM observations of strong nebular emission lines using the stellar SED as input for the Cloudy photoionization code. |
4:00-5:00 PM | Splinter Session 2: ApogeeReduction.jl | Room TBD |
4:00 PM | Discussion Session | Kevin McKinnon and Andrew Saydjari |
5:00 PM | Transportation |
Friday June 6th 2025 |
8:30 AM | Transportation |
9:00-9:30 AM | Session 11 | Chair: Emily Griffith |
9:00 AM | Status of the 'After Sloan 5' Steering Committee | Peter Frinchaboy |
The 'After Sloan 5' Steering Committee (AS5SC) co-chairs will give a short update and take questions about the status of the AS5SC process to that point. |
9:12 AM | LVM in the AS5 Era | Guillermo Blanc |
SDSS-V successfully commissioned the Local Volume Mapper Instrument (LVM-I) at Las Campanas Observatory (LCO) in late 2023 (Drory et al. 2024). For the last year and a half we have been operating the largest on-sky IFU, mapping the Milky Way plane and the Magellanic Clouds with one of the most sensitive low surface brightness spectroscopic instruments in the world. While the LVM data we have accumulated so far is “jaw-dropping” and the survey efficiency meets our original predictions, the full potential of this instrument is yet to be realized. I will present science ideas and plans to continue the operations of the LVM-South facility for another 5 years, to establish a rich database of faint lines on key Milky Way nebular targets and explore a so far unseen and uncharacterized low surface brightness universe, pushing the extremes of the spectral panopticon, mapping the largest MW ionized structures, revisiting key regions of the MW with multiple dithers to increase both depth and spatial resolution by a factor of 2-3, and exploring new extra-galactic science that LVM-I is in a unique position to tackle. |
9:30-10:30 AM | Splinter Session 3: MWM Methodologies | Room TBD |
9:30 AM | Minimizing Assumptions, Maximizing Insights: A Differential Analysis of Star Cluster Chemistry | Madeleine McKenzie |
The moment starlight meets a telescope’s mirror, astronomers begin making assumptions. Large spectroscopic surveys have transformed our understanding of the Universe, however, determining precise stellar abundances remains fraught with systematic uncertainties. These arise from fundamental assumptions about critical components such as line lists, model atmospheres, and non-local thermodynamic corrections, as well as from the techniques used to infer stellar parameters. These uncertainties obscure subtle chemical signatures, blurring trends between stellar populations. A powerful way to mitigate these uncertainties is through a differential, line-by-line analysis of carefully selected stellar samples. This talk will explore how such an approach reveals intrinsic elemental dispersion within a system, offering a clearer, less biased measure of abundance variations in a star cluster. As a proof of concept, I will describe the analysis of Potassium abundance distribution in Omega Centauri using APOGEE spectra. By examining absorption-line equivalent width variations, I aim to help constrain enrichment mechanisms and cluster formation processes. This approach complements ASPCAP and future spectroscopic pipelines, working alongside these datasets to extract more nuanced chemical variations. Expanding differential abundance techniques to other stellar populations will deepen our understanding of chemical evolution in star clusters and beyond. |
9:46 AM | LTE vs. NLTE Differences in Stellar Parameters and Chemical Abundances for APOGEE | Pierre Thibodeaux |
The Galactic Genesis program of the Milky Way Mapper aims to better characterize the chemodynamic structure of the Milky Way by obtaining near-infrared APOGEE spectra of ~4 million red giant stars in the Milky Way. Its analysis pipeline, ASPCAP, uses precomputed synthetic spectra to fit observed spectra for stellar parameters and chemical abundances. These synthetic grids are computed assuming Local Thermodynamic Equilibrium (LTE), which breaks down in the cooler and more luminous red giants that are the main target of Galactic Genesis. In addition to affecting the measured chemical abundances, this potentially manifests as systematic offsets in the spectroscopically inferred effective temperatures and surface gravities, which ASPCAP corrects with empirical relations to agree with photometric and asteroseismic surface gravities. Fitting with non-LTE (NLTE) synthetic spectra instead may allow us to obtain accurate stellar parameters and chemical abundances without calibration. We use Turbospectrum to generate LTE and NLTE synthetic spectral grids over a range of effective temperatures, surface gravities, metallicities, and chemical abundances, using NLTE models computed by the MPIA group. To enable rapid fitting, we then train neural network emulators (the Payne) on the spectral grids. We explore the discrepancies that result from fitting APOGEE DR17 spectra with LTE and NLTE neural networks, and characterize important differences. |
9:58 AM | Empirical Scaling Laws for Stellar Spectra Emulation with TransformerPayne | Tomasz Różański |
Spectroscopic surveys in astronomy have reached unprecedented scales, necessitating efficient computational methods to analyze stellar spectra. Neural-network-based emulators have emerged as essential tools, enabling rapid and accurate approximations to computationally intensive spectrum synthesis models, accelerating stellar parameter and abundance inference. However, these methods can still exhibit systematic errors and limited transfer learning capabilities. Enhancing transfer learning facilitates adapting models to incorporate additional physics with only a few supplementary samples. Insights from natural language processing suggest scaling datasets, model capacity, and training budgets can predictably improve performance and foster the emergence of interpretable features—valuable not only because they encode underlying physics but also because they enhance transfer learning capabilities. We investigate scaling laws for stellar spectra emulation, specifically focusing on the TransformerPayne architecture. We explore how emulation accuracy scales across three key dimensions: (1) the size of the stellar spectra grid, (2) neural network capacity, and (3) computational resources allocated for training. Using a representative grid of 100,000 synthetic stellar spectra, we empirically quantify how each scaling dimension independently contributes to improvements in emulator accuracy. Our results clearly demonstrate power-law relationships that hold across a wide range of scales: increasing the training dataset size by an order of magnitude reduces emulation errors by roughly a factor of 20, while a similar increase in neural network size independently reduces errors by roughly a factor of 15. We also address practical aspects of scaling, highlighting the critical importance of careful hyperparameter optimization and proper network initialization to ensure stable training dynamics. By identifying these robust scaling relationships, we provide concrete guidelines on optimal resource allocation for computational budgets and stellar grid sizes. Ultimately, these insights will support the ambitious requirements of next-generation spectroscopic surveys and catalyze further advancements in stellar spectroscopy. |
9:30-10:30 AM | Splinter Session 3: LVM Emission Line Physics and Diagnostics | Room TBD |
9:30 AM | Discussion Session | TBD |
9:30-10:30 AM | Splinter Session 3: Future Data Releases Discussion | Room TBD |
9:30 AM | Discussion Session | Anne-Marrie Weijmans |
10:30-11:00 AM | Coffee |
11:00-12:30 PM | Splinter Session 4: MWM & LVM | Room TBD |
11:00 AM | Discussion Session | TBD |
11:00-12:30 PM | Splinter Session 4: Stellar Ages | Room TBD |
11:00 AM | Predicting RGB Ages from Abundances, and Anomalies in this Relationship | Polly Frazer |
In the Milky Way a general trend links star age to element abundance, as young stars tend to be metal rich while old stars tend to be metal poor. Utilizing a dataset of 6676 stars, their [Mg/H] and [Fe/Mg] abundance ratios and effective temperatures, we have created an age predictor for red giant branch stars, using a k-dimensional tree to predict each star’s age given the median of its neighbors within the abundance and temperature space. However, we have robustly identified significant outliers to this trend, whose surface abundances do not align with their predicted ages, suggesting an interesting history. We split these outliers into 2 groups: 132 of the stars are metal rich and show signs of young asteroseismic age, which we denote as young alpha rich (YAR). 51 are metal poor and show signs of old asteroseismic age, which we denote as old alpha poor (OAP). Are these stars genuine age outliers, or have they potentially undergone mass transfer? Without any drastic differences in kinematics, UV flux and other stellar abundances between these candidate groups and their controls, the identification of these stars is a step towards better understanding stellar histories, and poses a potential limit to asteroseismic age data for these stars. |
11:12 AM | APOTESS: Combining spectroscopic and asteroseismic measurements for evolved stars observed in the TESS mission | Madeline Howell |
Building on the legacy of the APOKASC and APO-K2 catalogs, we propose a new catalog – APOTESS – that will utilise spectra from SDSS-V and asteroseismic measurements from the all-sky photometric mission, TESS. With TESS, it is initially estimated that we will be able to measure accurate masses and ages for ~400,000 subgiant and red giant stars. However, this candidate sample could be as large as 7.5 million, and as such there should be a large overlap with the Milky Way Mapper (MWM) survey. By combining asteroseismic and spectroscopic measurements, we can investigate areas of Galactic chemical evolution and stellar evolution. For example, measuring accurate ages for stars in the Milky Way, mapping the mass loss in cool RGB stars with metallicity, calibrating [C/N] masses and ages, and studying different populations in our Galaxy such as alpha-rich young stars and stellar streams. This sample will also increase the number of characterised exoplanet host stars with measured stellar parameters. In the APOTESS catalog, we aim to include red giants from clusters to take advantage of the OCCAM survey and the globular cluster observed in MWM. This will enable us to accurately constrain ages for each cluster, measure the integrated mass loss, study the multiple populations in globular clusters, and investigate potential merger/mass transfer candidates. Furthermore, the TESS Continuous Viewing Zones at the celestial poles have over two years of observations. This photometry is approaching the exceptional quality of the Kepler data and represents a ‘Gold Sample’ of asteroseismic measurements with TESS. This high-quality data will enhance investigations on Galactic chemical evolution and stellar evolution, such as unambiguously distinguishing evolutionary phases using detections of mixed modes, studying the internal stellar structure with comparisons to detailed models, and measuring stellar rotation rates. |
11:24 AM | Galactic Archaeology with [C/N] and Red Giants | Jack Roberts |
[C/N] can be used to derive ages for Red Giants stars due to the First Dredge-up. I use APOKASC3 to calibrate a [C/N]-age relationship for APOGEE DR17 and apply it to APOGEE stars throughout the Milky Way. I find that the predictive power of [C/N] remains even for luminous giants and core-He burning stars. Other age methods, such as asteroseismology, have complications for getting ages for these stars due to mass loss or the weakening of the asteroseismic scaling relations, making red giant [C/N] a powerful tool for galactic archaeology. Using [C/N], I predict ages for a large sample of stars across the Milky Way. With this sample, I find that the average [Fe/H] of stars formed at a given radius has been the same for the past ~8 Gyr. This implies an equilibrium between dilution from in-falling gas and pollution from SNe, as well as an unchanging radial metallicity gradient. Additionally, I examine the width of the metallicity distribution function versus age and Galactocentric radius and compare with predictions from radial migration models. |
11:36 AM | Discussion Session | Alexander Stone-Martinez & Lucy Lu |
11:00-12:30 PM | Splinter Session 4: PyNeb Tutorial | Room TBD |
11:00 AM | Discussion Session | Tony Wong |
Participants are advised to join the SDSS Github organization so they can access the sample notebooks at: github.com/sdss/lvm_early_science/tree/main/pyneb_demo |
12:30-1:30 PM | Lunch | |
1:30-2:00 PM | Wrap-up of week |
2:00-3:30 PM | Splinter Session 5: Galactic Genesis & MWM Selection Function | Room TBD |
2:00 PM | A Galactic Self-Portrait: Density Structure and Integrated Properties of the Disk | Julie Imig |
The Milky Way can be studied in more detail than any other galaxy in the Universe, with precise ages, positions, and chemical compositions obtainable for hundreds of thousands of individual stars. However, many standard galactic properties of the Milky Way such as the total radius, stellar mass, star formation history, and optical colors remain difficult to estimate from our inside perspective, preventing direct comparison between the MW and the broader population of galaxies in the universe. In this study, we derive the stellar density profile of the Milky Way disk as a function of stellar age, metallicity, and alpha-element abundances using the final data release of the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. These results are applied to produce new estimates of the integrated properties of the Milky Way, including the total scale length, (g-r) colors, and spectral indices from its integrated light spectrum. The present-day Milky Way is best classified as a "green valley" galaxy, most closely matching the properties of massive red spiral galaxies in the local universe. |
2:12 PM | Reconstructing the Milky Way using an orbit superposition approach and SDSS data | Sergey Khoperskov |
In this talk, I will introduce a novel orbit superposition method designed to reconstruct the entire Milky Way far beyond its current observational coverage. By leveraging 6D phase-space information from Gaia and APOGEE, this approach provides a selection-function-independent snapshot of our Galaxy. I will present the chemical abundance patterns, kinematic properties, and age structure of stellar populations across the Milky Way’s disk, bar, and bulge. Furthermore, I will discuss the Milky Way’s evolutionary history and show the true impact of various non-equilibrium processes on its present-day structure. |
2:24 PM | Radial Gas Flows in Disk Galaxy Chemical Evolution | James Johnson |
Disk galaxies like the Milky Way are expected to experience radial gas flows carrying matter toward their centers. Observationally, there are no obvious signs of these flows at speeds larger than a ~few km/s. In this talk, I will demonstrate that radial gas velocities on the order of ~1 km/s have a sufficiently large impact to play a central role in metal enrichment. While substantial, the only direct effect is mixing, and most of the influence of radial flows can be understood from this perspective. An inward gas flow funnels low metallicity gas into high metallicity regions, and therefore always carries the effect of dilution. With other parameters held fixed, a 1 km/s radial velocity in the interstellar medium removes half of the oxygen from the solar neighborhood. An important indirect effect of radial flows arises when models are constrained to form a galaxy of a particular mass and surface density gradient, such as the Milky Way. In these cases, faster gas velocities shift metal-poor accretion to larger Galactocentric radii, which steepens the radial metallicity gradient. Broadly, different prescriptions for radial flow velocities can be placed into two categories based on whether the flow acts as a source or a sink of mass at a given location in the Galaxy. If the flow acts as a sink, then metallicity becomes nearly time-independent during the thin disk epoch, and can vary by as little as 0.1 dex over the last ~6-8 Gyr of star formation. This effect offers an attractive explanation to the seemingly age-independent metallicities observed in young and intermediate-aged stellar populations in the Milky Way. In the context of recent observations, these results suggest that radial gas flows may be much more closely associated with spiral structure than bars, contrary to long-standing theoretical expectations. |
2:36 PM | Discussion Session | Jianhui Lian |
2:00-3:30 PM | Splinter Session 5: LVM Data & LVM DR20 Discussion | Room TBD |
2:00 PM | Discussion Session | Hector Ibarra-Medel, Sebastian Sanchez & Anne-Marie Weijmans |
2:00-3:30 PM | Splinter Session 5: BOSS (BHM) Data Tutorial | Room TBD |
2:00 PM | Discussion and Tutorial Session | Sean Morrison |
3:30-5:00 PM | Splinter Session 6: Magellanic Genesis | Room TBD |
3:30 PM | Azimuthal variations in chemical abundances in the LMC | Joshua Povick |
The LMC is an excellent laboratory for galactic archaeology because it allows for the resolution of individual stars, which is typically not possible for galaxies beyond the Milky Way (MW). This work investigates the azimuthal abundance variations in the LMC using giant stars. It is inspired by previous studies in the MW that have demonstrated correlations between these variations and galactic structure (e.g., Hawkins 2023; Hackshaw et al. 2024). Due to the known structural features of the LMC, such as the northern spiral arm feature formed by a recent interaction with the SMC and the east-west bar, similar analogous variations are expected. The data for this work comes from the SDSS V Milky Way Mapper (MWM) and has coverage out to 11 deg with over 20 measured elemental abundances. The initial results reveal azimuthal variations of up to ~0.1 dex in some cases, as well as variations covering structures associated with the past LMC-SMC interaction about 2 Gyr ago. These findings reinforce the connection between physical structure and chemical enrichment in the LMC, providing insight into its evolution. |
3:42 PM | Unveiling Milky Way–LMC properties from All-Sky Kinematics of the Galactic Halo | Yanjun Sheng |
The gravitational interactions between the Milky Way (MW) and the Large Magellanic Cloud (LMC) induce dynamical perturbations in the MW halo, affecting the density and kinematics of halo stars. These perturbations vary across different MW-LMC models, providing a unique way to probe the properties of both galaxies. In this work, we build a grid of ~ 2000 high-resolution (10^7 particles) N-body simulations of the MW-LMC interaction, exploring a broad range of halo masses and shapes for the two galaxies. We find that the magnitude of the LMC-induced perturbation is significantly reduced when transitioning from a first-infall to a second-passage orbital scenario, with the latter not matching our observational results from RR Lyrae stars. This provides critical insights into the LMC's orbital history. In addition, leveraging our simulation results, we develop neural-network-based emulators to model both the first-moment (mean velocity) and second-moment (velocity dispersion) kinematic summary statistics of halo stars as functions of the model parameters. We evaluate the efficacy of current and future observational datasets—including measurement uncertainties in stellar distances and velocities—in constraining these parameters and identify an optimal parameter set that best matches the kinematic signatures observed in our RR Lyrae data. Our work extends beyond traditional point estimates of the MW-LMC parameters from the LMC-induced perturbations in the MW halo, establishing a robust probabilistic understanding of parameter uncertainties and correlations. |
3:54 PM | A Red Clump Perspective on Magellanic Cloud Distances | Slater Oden |
The Magellanic Clouds are the closest interacting galaxy pair to the Milky Way, with a complex history of dynamical interactions that have shaped their present-day structure and star formation history. In this study, we use a large statistical sample of red clump (RC) stars from Gaia DR3 to investigate the distances and morphology of the Magellanic System. To account for extinction, we apply reddening corrections using the OGLE-IV and Schlegel et al. (1998) reddening maps. We derive absolute magnitudes and corresponding distances for the Magellanic RC stars using the most recent Gaia empirical photometric calibrations from Ruiz-Dern et al. (2018), which account for (G - Ks) color—and, by extension, metallicity. Through this analysis, we construct the most detailed and accurate distance maps of the Magellanic Clouds, as traced by their RC populations, revealing peripheral substructures such as the LMC southern hooks, the northern arm, the Magellanic Bridge, and the SMC northern overdensity. Notably, we confirm the distance bimodality in the eastern SMC, present evidence that the LMC warp extends fully azimuthally around its periphery, and show that the LMC southwestern hook (northern arm) is significantly closer (farther) by ~3 kpc compared to the rest of the LMC’s southwestern (northeastern) periphery. These results will establish the foundation for the most precise derivation of 3D cylindrical velocities relative to the LMC disk plane using SDSS-V BOSS spectroscopy, enabling an unprecedented analysis of the kinematics of periphery populations. |
4:06 PM | Discussion Session | David Nidever |
3:30-5:00 PM | Splinter Session 6: LVM Sky Subtractions | Room TBD |
3:30 PM | Discussion Session | Amy Jones & Knox Long |
3:30-5:00 PM | Splinter Session 6: AGN Catalogs | Room TBD |
3:30 PM | Discussion Session | Andrea Merloni |
5:00 PM | Transportation |