Rubin Science Assembly
Weak lensing with Abell 360
Thu Nov 13 2025
Rubin Science Assembly
Today’s Agenda
2
9:00 am: Announcements
9:05 am: Background of Abell 360 (Shenming)
9:10 am: Notebook tutorial + Q&A (Shenming)
9:35 am: Notebook tutorial + Q&A (Shenming)
Questions are welcome at any time. Raise your hand or post in the Zoom chat.
Rubin Science Assembly
Announcements
3
Operations has begun!
LSST@LATAM: Dec 1-5 2025, Mexico City
AAS 247 Winter Meeting: Jan 4-8 2026, Phoenix, AZ
Upcoming Rubin Science Assemblies:
Rubin Science Assembly
Introduction to the Users Committee
4
The Rubin Users Committee is charged with:
Charge: rdo-051.lsst.io
Website: rubinobservatory.org/for-scientists/committees-teams/users-committee
Reports: available in the Rubin Community Forum (community.lsst.org/tag/users-committee)
Meetings: two formal meetings per year, which always start with an open community listening session
Contact: via email to RubinObs-Users-Committee@lists.lsst.org or via the Rubin Community Forum
(go to Community.lsst.org and send a direct message to the @Users-Committee group)
Feedback: use the Google form at forms.gle/km4VS2r2uYrvJ2w58
The Rubin Users Committee looks forward to hearing from the Rubin science community.
Igor Andreoni Dominique Boutigny Alejandra Muñoz Arancibia
Anupreeta More Vincenzo Petrecca Vicki Sarajedini Matthew Holman
Darryl Seligman Anja von der Linden Matthew P. Wiesner Michael Wood-Vasey
Vera C. Rubin Observatory | Users Committee | 2024-2025
LINCC Frameworks Office Hours
5
LINCC Frameworks mission is to enable scientists by developing scalable and productionised software/algorithms in collaboration with broader community.
LINCC Frameworks Projects
Office Hours provides users an opportunity to learn about or get support for LINCC Frameworks software.
When: Most Thursdays 1pm ET / 10am PT / 7pm CET (see LF Calendar)
Where: Zoom (zoom link)
You can also submit questions via the #lincc-frameworks-qa slack channel and sign up for the LINCC mailing list for more updates (instructions).
Website
Abell 360
Early this year, the cluster commission team (led by Anja von der Linden) wanted to pick a galaxy cluster to test cosmological analysis, especially weak lensing.
Abell 360 is a galaxy cluster covered by DP1 with sufficient observations (SV_38 field).
Abell 360 is a massive cluster (M500,SZ ~ 6 × 1014 Msun) at median redshift (z~0.2).
→ It produces significant lensing effects.
Various tests have been done on Abell 360 using DP1 data.
6
Tutorial 103.6. by A.A.Plazas et al for making this figure.
Rubin Science Assembly
Technotes and paper
SITCOMTN-154: Initial studies of photometric redshifts with LSSTComCam from DP1 (Charles et al.).
SITCOMTN-161: PSF assessment in the field of Abell 360 and shapeHSM shear profile using LSSTComCam data (Combet et al.)
SITCOMTN-162: Testing the implementation of Metadetection and Cell-Based Coadds on Abell 360 LSSTComCam data (Gorsuch et al.)
SITCOMTN-163: Source Selection for Abell 360 in LSSTComCam Data Preview 1 (Adari et al.)
SITCOMTN-164: AnaCal Shear Profile of Abell 360 in LSSTComCam Data Preview 1 (Li et al.)
SITCOMTN-165: Surface brightness profiles around massive galaxies in LSSTComCam data (Zhou et al.)
……
DESC paper: A Rubin View of Abell 360 (led by Anja, to be submitted)
7
Rubin Science Assembly
LSST and Cosmology
Geometry of the Universe
Angular diameter distance: standard ruler (BAO), SL
Luminosity distance: standard candle (SNIa)
Matter in the Universe
Power spectrum: WL
Growth of structure
Halo mass function: galaxy clusters
8
Also joint analysis! e.g., 3x2 cross correlations – shear-shear, (number) density-density, and shear-density (both cosmic shear and clustering)
BAO: Baryon Acoustic Oscillation
SL: Strong Lensing
SN Ia: Type Ia Supernovae
WL: Weak Lensing
Rubin Science Assembly
9
Our scientific aim: Exploring the physics of the Dark Universe
Dark energy, dark matter, neutrinos and signatures of inflation
Our approach: Combining (at least) five cosmological probes:
visit https://lsstdesc.org/ for more details
For DESC membership
(LSST Data Rights required),
apply here
Rubin Science Assembly
Background on red sequence and weak lensing
Galaxy clusters show a typical red sequence of galaxies (color-magnitude diagram).
Using colors one can select background galaxies (e.g. redder).
The mass of the cluster bends the light of background galaxies, distorting their images.
Using the gravitational lensing effects, one can infer the foreground mass.
10
Rubin Science Assembly
Weak lensing vs Strong lensing
Strong lensing shows clear arcs (lower left, cluster center), but weak lensing is difficult to see directly (upper right, far from the center) and requires statistics of galaxy shapes to be detected.
Weak lensing can detect mass in a much larger area.
11
Simulation from Mellier 1999
true
shear
mean
ellipticity
tangential direction
e1
e2
two components of ellipticity
Rubin Science Assembly
Weak lensing
The source is magnified and distorted by lensing.
12
In weak lensing, the lensing shear can be measured from the mean shape of background galaxies.
Rubin Science Assembly
Let’s take a look at Abell 360 in DP1 first
HiPS map on Portal:
Target: Abell 360
FoV: 0.1 deg
Image: ugri
→ Search
Note, there is no clear strong lensing effect (arcs, Einstein ring), but only weak lensing effect – the distortion is approximately ~10% of the ellipticity of background galaxies.
13
Rubin Science Assembly
Tutorial: Red sequence of Abell 360
Go through the notebook.
14
Rubin Science Assembly
Tutorial: Weak lensing with Abell 360
Go through the notebook.
15
Rubin Science Assembly