2019 SB Gaia Sprint
Wrap-up — KITP — 2019-03-29
2019 SB Gaia Sprint
Wrap-up — KITP — 2019-03-29
Hans-Walter Rix (MPIA, Heidelberg)
Learned many things, among them
Homework: help Anthony Brown find X MEuro to “do the selection function”
Ellianna Schwab Abrahams (UC Berkeley, CTDI)
What Worked (Time Domain Gaia):
What Didn’t Work (yet!):
CV in both TESS + Gaia Alerts
Thanks Rix, Brown, Casey, Hogg, Price-Whelan,
Gaensicke & Gaia DPAC!
Alice Quillen (Rochester)
I tried using current velocities and backwards orbits of moving groups, listed by Gagne+18 and with ages less than 60 Myr years, to see if the stars in them formed near spiral arms and find out where were the arms?
Young moving groups seem associated with the “Local spur”. This arm may have wound up -- or two different armlets are required.
Now 60 Myr ago
-Ringing might have also been caused by a dwarf plunging through the center of the Galaxy.
-VVV measuring proper motions in the bar’s X (resonant model for vertical heating?)
Galactocentric angle degrees
Joel C. Zinn
Ohio State University
Semyeong Oh (Cambridge)
Linear velocity field of 40 m/s/pc
may be detectable with
astrometry + DR2 (statistical) noise
+ 30% RV (1 km/s uncertainty)
for the Hyades cluster.
Max Planck Institute for Astronomy
Thanks to Sarah, Hogg, Ortwin, Chervin, Larry & Hans-Walter
(Flatiron Institute, CCA)
Compared the velocity tensor elements of Eilers’ & Hogg’s APOGEE/Gaia data to the velocity tensor elements of simulated bars
I did this
….what we should expect to see in the various terms of the velocity tensor
We see the bar in APOGEE/Gaia data and it looks similar to simulated bars
[Will insert plots]
Comparison to Eilers’ plots
with Eilers, Hogg, Laporte, D’Onghia, Rix
and advise from Price-Whelan, Gerhard, Widrow
David W Hogg
(NYU) (MPIA) (Flatiron)
The radial-velocity variations we see (with APOGEE & Gaia) in the Milky Way disk are going to provide evidence for density variations.
(Eilers, Pearson, Laporte)
Related to this, I formulated a method to use disk simulations to build an
empirical-theoretical model of disk patches.
If we are seeing the bar at the Galactic Center, it is at the wrong angle!
(Gerhard, Widrow, Pearson, Laporte, Rix)
We need to sharpen up a proposal to build a set of Gaia selection functions.
(Brown, Fouesneau, Rix, Casey, Price-Whelan)
(University of Wisconsin - Madison)
What I did:
Compare the contributions of different sectors of the U-V plot in different volumes to begin to disentangle moving groups from open clusters
What I Learned:
Getting to work on astronomy research all day is even better than I thought
Cosmological galaxies are not
in an inertial frame
What I learned this week:
Velocity of disk COM relative to halo COM
Acceleration of COM calculated different ways
So….where are we building our models again?
….even when there’s no LMC...
Position of disk COM relative to halo COM
theme of the week: diffuse disequilibrium
(in science and life)
Andrew Wetzel (UC Davis)
(stolen from Sanderson)
Siddharth Mishra-Sharma (NYU)
Alexandra Borukhovetskaya(University of Wisconsin - Madison)
undergraduate student working with Elena D’Onghia
What I came to do:
Learn Arcturus ages, metallicities, and clustering techniques.
What I did:
What I plan to do in the future:
Continue modifying and improving the algorithm to find new members and gain insight into the origin of Arcturus.
Harshil Kamdar (Harvard)
What I Did: finished writing up a paper on v wide (>10 pc) co-moving pairs due to disrupting star clusters in the disk, worked w/ Coronado & Rix on interpreting small-scale structure in combined chemodynamical space (Gaia+LAMOST).
What I Learned: sampling points to follow a correlation function is hard
ICC University of Barcelona
-Red Clump & Giants RVS samples corrected using cross match to 2MASS - thwarted at the last minute by a string encoding problem in Pandas.
-GPflow & GPyTorch running in 2D with heteroskedastic noise (i.e. uncertainties - surprisingly non-trivial).
-GPR on e.g. vRvR data (left) - needs work.
-Derivatives of latent function f(x) with GPflow machinery (1D example above) - still quite rough, red line should match green line.
Anthony Brown (Leiden Observatory)
What I did
select source_id, ra, ra_error, dec, dec_error, parallax, parallax_error, parallax_over_error, pmra,pmra_error, pmdec, pmdec_error, ra_dec_corr, ra_parallax_corr, ra_pmra_corr, ra_pmdec_corr, dec_parallax_corr, dec_pmra_corr, dec_pmdec_corr, parallax_pmra_corr, parallax_pmdec_corr,
pmra_pmdec_corr, radial_velocity, radial_velocity_error,phot_g_mean_mag, phot_bp_mean_mag, phot_rp_mean_mag, bp_rp, g_rp, bp_g,
2.5/log(10)*phot_g_mean_flux_over_error as phot_g_mean_mag_error,
2.5/log(10)*phot_bp_mean_flux_over_error as phot_bp_mean_mag_error,
2.5/log(10)*phot_rp_mean_flux_over_error as phot_rp_mean_mag_error,
sqrt(astrometric_chi2_al/(astrometric_n_good_obs_al-5)) as uwe
and radial_velocity is not null
and rv_nb_transits > 3
Do some radial velocity cleaning...
What I learned
Cecilia Mateu (UdelaR)
What I Did+Learned:
Sukanya Chakrabarti (RIT)
Worked on : what caused the disturbances in the outer HI disk of the Milky Way ?
Sampling Gaia PMs
(Shanghai Astronomical Observatory)
Pal 5 from Photometry
Sprint & Eugene Vasiliev (IoA, Cambridge)
Thx for the advice from Nora, Adrian, David, and Giuliano !
Motivation and Future Plans:
You will see magic happens after combining probabilities from photometry & astrometry in Eugene’s slide!
Sprint & Tadafumi Matsuno (PhD student, NAOJ) and Kohei Hattori (U of Michigan)
You will see what we can infer from the slices in Kohei’s slide!
Eugene Vasiliev (Institute of Astronomy, Cambridge)
Search for tidal tails around globular clusters with Gaia astrometry and DECam photometry
With Zhen Yuan and valuable advice from Adrian, Ana, Sarah P., Jason H., Nora, Giuliano
Learned Gaussian ProcessesⓇ, Matched FilteringTM.
Developed the membership selection pipeline combining Gaussian Mixture for parallax+PM and Matched Filtering for CMD
Re-discovered tails around Pal 5, NGC 288.
Not found anything around NGC 5897, NGC 7089, …
Plan to continue the search for other cluster tails...
Kohei Hattori (U of Michigan)
phase-space slice of the Gaia Sausage
With Tadafumi Matsuno (PhD student, NAOJ) and Zhen Yuan (SHAO).
StarGO package (by Zhen Yuan) is powerful in finding substructure.
Red: Solar neighbor / Black: total sample
Elena D’Onghia (work with Boquan Chen)
We use SNN algorithm (Chen et al. 2018) to cluster in 5 dimension to
rebuild Orion. Two clumps are newly discovered.
This approach opens us the possibility to study how star formation occurs in Orion.
This is an example of the superiority of SNN on DBSCAN.
(2)-(3) DBSCAN recoves one group
(4) SNN recovers both groups
Lorenzo Rimoldini (University of Geneva, CH)
Classification of variable objects in all Gaia DR2 (without time series):
> better than you might expect
>> it can be useful before DR3 (SDSS-V, TESS, ...)
>>> help in gathering rare variable classes
>>>> millions of new variable candidates soon!
Learned about streams, complementary data sets, interesting color-color plots combining optical, IR and radio, features of AGBs in the radio band, some details about Gaia as well :)
Please email me by the end of April if you want to make sure your class of interest is included!
Giuliano Iorio (Institute of Astronomy, Cambridge)
Membership likelihood for RRLs in Pal 5 stream
Thanks to Cecilia, Adrian, Nora, Eugene, Elianna for advice and useful discussions
What I did:
Learned: Galstreams, what is a GP, a lot of interesting way to use Gaia Data.
What I found:
A lof of RRLs!!
To do: Improve background model, analyse other streams, Pal5 stream model.
No other variables
Productive discussions on phase space spirals with Kathryn, Chervin … radially plunging satellites with Heidi, and GP blah blah blah with Lauren and Hamish, to be continued in Gaia “brisk walk” during and after the conference
Gauthier, Dubinski, LMW 2006
LMW, Chequers et al 2014
Spekkens & Sellwood 2007
Infer surface density from moments of the velocity field --- here, a linear model on pixels of simulation.
Probably makes more sense to go after the FR , Fphi...learn rather than assume the Jeans/CBE (cf. Alice and Hamish)
<Vz> <Vphi> <zVz>
<Vz^2> Var(Vphi) <VRVphi>
Density model residual
for helpful advice and questions
Sample of 11475 metal-poor MSTO candidates; ~50% complete and ~89% pure
RGB selection is still in progress, but will have lower completeness (~25%) and purity (~67%)
I learned: (1) It works!
(2) How to cross-match on the Gaia Archive
(3) The memory limit of my laptop
Color code: amplitude of local corrections with respect to DR2.
Some catalogs: no patterns
Others: stripes along RA or Dec + large scale patterns.
Banding due to old ground-based positions used to build proper motions. Larger scale patterns: reference system differences, or rotation.
Adventures in de-biasing old asteroid astrometry.
TODO: apply to DR2 pm correction for rotation (Lindegren’s doc); check current results vs. astropy method for position propagation.
Discovered this week: interesting intersections between dynamics in the Galaxy and the Solar System…. Ideas for an article! ….Sprinting ! It works!
Juna Kollmeier (@ Doc right now unfortunately)
GG Catalog Progress
GG Brown Dwarfs: Faherty (Done)
GG White Dwarfs: Gaensicke (Done)
GG: CMD: Brown (Done)
GG: 6D Phase Space: Brown (Done)
GG Spiral (Is there a spiral?)
GG Red Clump (Hawkins?)
GG Low Z (Simon?)
Where to host these?
I’m Andy Casey (Monash) and this week I self-calibrated and simulated the astrometric and radial motion jitter for single stars (w/ Rix and Price-Whelan)
the “binary fraction”
Jason Sanders (IoA, Cambridge)
Aim: 3d bulge kinematics from RVS
Distances from isochrones → in front of bulge?
But net rotation about ~ 8kpc → distances OK
[Fe/H] & Teff from random forest on WISE & 2MASS
Vertical met grad.
Newberg et al. (2007)
Re-discovering & confirming stellar streams
m-M = 14 - 18.5
[Fe/H] = -2
Age = 12 Gyr
Alexa Villaume (University of California Santa Cruz)
Observed color - Synthetic color
Asked a lot of questions about sources of uncertainties and quality flags in DR2 (thank you Anthony and Morgan!)
Learned: Apples-to-apples comparisons between synthetic and observed photometry is complicated and many corrections are needed
Timothy Brandt, UCSB
Kareem’s wide binaries can calibrate parallax uncertainties. Formal uncertainties are 20-30% underestimates? Only addresses spatially uncorrelated errors...
Hints of magnitude-dependent zero-point offset (couple μas/mag)?
Emily Cunningham (UCSC)
Adrian Price-Whelan (Princeton)
w/ Cecilia Mateu: coordinate frames for stellar streams in galstreams
→ Next: we will clean up the library and provide other metadata for streams
w/ Nora Shipp: what “known” streams in the north can be confirmed?
→ Next: compute significance for candidate rediscoveries, repeat with DECaLS?
w/ Cecilia+Giuliano Iorio: RR Lyrae in the Pal 5 stream, >15 candidates
→ Next: fit stream models to new distance information, improve MSTO filter
w/ Ana Bonaca: Improving models of the GD-1 stream
→ Next: Figure out what is going on with the stream track?!
2D density model
P5. Astro Viz work! Thanks to Nora for data on Streams! Movies forthcoming
SiO maser emission
No Coincidences in Gaia
Coincidences in Gaia+2MASS (~400, %100 MIRA!)
David Mykytyn, New York University
Morgan Fouesneau (MPIA, Heidelberg)
What I learned this week among other things
What I did this week
Not looking at stars - epic fail!
No coherent rotation
Consistent with random
Van der Marel et al. 2019
- Analytic modeling of disequilibria using the continuity equation with Larry and Hamish: can’t resolve all degeneracies, yet.
- Accelerations for Hipparcos-DR2 x-matched stars (courtesy T. Brandt), definitely worth exploring!
- Great breakout on simulations and mock catalogs. Got a flavor of the diversity of philosophies and techniques, going into the available codes, and, most importantly, their scope depending on the scientific problem at hand.
> Worked on:
- Responded to referee report for a paper on estimating the local DM content in the solar neighborhood; mild evidence of ‘excess’ matter density (also verified by A. Widmark using an independent technique).
- Will better disequilibria modeling only improve precision and rule out the excess? Can only answer on a case-by-case basis.
- Baby step: started simulating effect of DM halo (final goal: NFW population) + test particle disk on a stellar distribution using galpy potentials (thank you J. Hunt). [Bummed couldn’t make at least 1 pretty plot! :(]
- Implemented A. Brown’s RUWE cut and found no significant change in derived results!
May Gade Pedersen
(KU Leuven, Belgium)
Recreated from Bastian+2018
What I did:
Constructed Gaia CMD of cluster with known eMSTO. Converted isochrone clouds to Gaia colours and ‘fit’ to observations.
Principles behind cluster membership
verification. Use appropriate Gaia
passbands for bolometric
Kareem El-Badry (UC Berkeley)
Twinning: excess of equal-mass wide binaries is real!
Made a catalog of 3000 hierarchical triples with RV-variable components
Lots of other ideas:
Thanks for great discussions with Rix, Casey, Gaensicke, Oh, Hogg, Fouesneau, Brown, Kamdar ++
Still working on the math ¯\_(ツ)_/¯
Jason Hunt (Dunlap/Toronto)
Talked about: Non-axisymmetric structure, actions, galpy, phase space spirals, actual spirals, bars
Worked on: Lots of little things, including paper draft from last sprint, and looked at models of different spiral structure
Simulations from Alex Pettitt
Ana Bonaca (Harvard)
Found GD-1 models with relative radial velocity offsets between the stream and the spur comparable to the observed offset
Lauren Anderson (Flatiron Institute):
Worked on building a 3D dust map of the Milky Way
Simulation: (Almost) reconstructed the “true” dust density in the Latte simulation, the foundation for Ananke. We have the right amplitudes and scales !!
Data: Applied to 105 dust estimates from Gaia with good parallax estimates
Hyper parameters: ℓ ~ 60 pc and σ ~ 80 M☉/pc3 (optimized from a more local sample)
Sihao Cheng Johns Hopkins University
Borja Anguiano (University of Virginia)
Kathryn V Johnston (Columbia)
?? PS-Spirals - where? when? what??
with Chervin Laporte and Larry Widrow
Did: orbits in axisymmetric MW potential
Jphi (=Lz!) => groups with shared history
dvz & dvR “hit” => z-vz spirals & R-vr sloshing
???? Towards the ORIGIN ????:
“Rewind” spiral in Jphi bins
test approach with N-body sims
limitations: impulsive assumption; local view; moving groups
red: rguide =9 kpc white: rguide =7kpc
Chervin F. P. Laporte (UVic)
PS-spirals (Larry, Kathryn, Anthony locally & Martin Cool Smith+Jason H+Jason S), finding the OLR with DR2 (Jason H), GP blablablah (Larry+Hamish), velocity field of MW (Eilers+Pearson+Hogg), Moving groups Arcturus (Elena D’Onghia)
Did: checked some quick dirty solutions to my problems, didn’t work… but looking forward to next 3 weeks :). Made this movie of the PS-spiral in overdensity to help you hypnotise your guests back home.
Learned: I might have to GP blablablah my way out of this with RC to do what I initially intended to do.