Constraining the multi-scale dark-matter distribution in CASSOWARY 31 with strong gravitational lensing and stellar dynamics
Open accessAbstract
We study the inner structure of the group-scale lens CASSOWARY 31 (CSWA 31) by adopting both strong lensing and dynamical modeling. CSWA 31 is a peculiar lens system. The brightest group galaxy (BGG) is an ultra-massive elliptical galaxy at z = 0.683 with a weighted mean velocity dispersion of σ = 432 ± 31 km s−1. It is surrounded by group members and several lensed arcs probing up to ≃150 kpc in projection. Our results significantly improve on previous analyses of CSWA 31 thanks to the new HST imaging and MUSE integral-field spectroscopy. From the secure identification of five sets of multiple images and measurements of the spatially resolved stellar kinematics of the BGG, we conduct a detailed analysis of the multi-scale mass distribution using various modeling approaches, in both the single and multiple lens-plane scenarios. Our best-fit mass models reproduce the positions of multiple images and provide robust reconstructions for two background galaxies at z = 1.4869 and z = 2.763. Despite small variations related to the different sets of input constraints, the relative contributions from the BGG and group-scale halo are remarkably consistent in our three reference models, demonstrating the self-consistency between strong lensing analyses based on image position and extended image modeling. We find that the ultra-massive BGG dominates the projected total mass profiles within 20 kpc, while the group-scale halo dominates at larger radii. The total projected mass enclosed within Reff = 27.2 kpc is 1.10−0.04+0.02 × 10 13M⊙. We find that CSWA 31 is a peculiar fossil group, strongly dark-matter dominated toward the central region, and with a projected total mass profile similar to higher-mass cluster-scale halos. The total mass-density slope within the effective radius is shallower than isothermal, consistent with previous analyses of early-type galaxies in overdense environments.
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Wang et al. [68] do not combine stellar kinematics with pixel-level image modeling, and only present joint posteriors for a conjugate point likelihood with kinematics.
“Wang et al. [68] therefore do not combine stellar kinematics with pixel-level image modeling, and only present joint posteriors for a conjugate point likelihood with kinematics, similar to what was done here.”
From Constraint on dark matter self-interaction from combined strong lensing and stellar kinematics in MACS J0138-2155 (2026) · cites this paper as Wang et al. [68]
Wang et al. [68] notes that combining strong lensing and kinematics measurements is a potential difficulty.
“Wang et al. [68], which also studied a strong lensing cluster, notes this as a potential difficulty in combining strong lensing and kinematics measurements.”
From Constraint on dark matter self-interaction from combined strong lensing and stellar kinematics in MACS J0138-2155 (2026) · cites this paper as Wang et al. [68]
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Cites
Contraction of dark matter galactic halos due to baryonic infall
Blumenthal, G. R., Faber, S. M., Flores, R., & Primack, J. R. (1986) · The Astrophysical Journal · doi:10.1086/163867 · Cited by 1,213 · see citing works
Gravitational detection of a low-mass dark satellite galaxy at cosmological distance
Vegetti, S., Lagattuta, D. J., McKean, J. P., Auger, M. W., Fassnacht, C. D., & Koopmans, L. V. E. (2012) · Nature · doi:10.1038/nature10669 · Cited by 386 · see citing works
Empirical constraints on the formation of early-type galaxies
Moster, B. P., Naab, T., & White, S. D. M. (2019) · arXiv · doi:10.48550/arxiv.1910.09552 · Cited by 55
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Research works printed but not linked: 8
- Bertin, E. 2006, in Astronomical Society of the Pacific Conference Series, Vol. 351, Astronomical Data Analysis Software and Systems XV, ed. C. Gabriel,
- Elíasdóttir, Á., Limousin, M., Richard, J., et al. 2007, arXiv e-prints, arXiv:0710.5636 · arXiv
- Fassbender, R., Böhringer, H., Nastasi, A., et al. 2011, New Journal of Physics, 13, 125014
- Fruchter, A. S. & et al. 2010, in 2010 Space Telescope Science Institute Calibration Workshop, 382-387
- Tacchella, S., Conroy, C., Faber, S. M., et al. 2021, arXiv e-prints, arXiv:2102.12494 · arXiv
- Wang, Y., Mao, S., Vogelsberger, M., et al. 2021, arXiv e-prints, arXiv:2111.08714 · arXiv
- Weilbacher, P. M., Streicher, O., Urrutia, T., et al. 2014, in Astronomical Society of the Pacific Conference Series, Vol. 485, Astronomical Data Analysis
- Yıldırım, A., Suyu, S. H., Chen, G. C. F., & Komatsu, E. 2021, arXiv e-prints, arXiv:2109.14615 · arXiv
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O’Donnell, J. H., Jeltema, T. E., Roberts, M. G., Nightingale, J., Flowers, A., & Aldas, D. (2026) · Physical Review D · doi:10.1103/hfgd-245k · Cited by 5 · see citing works
- Authors
- Wang, H., Cañameras, R., Caminha, G. B., Suyu, S. H., Yıldırım, A., Chirivì, G., Christensen, L., Grillo, C., & Schuldt, S.
- Affiliations
- Max Planck Institute for Astrophysics (DE)
- Institute of Astronomy and Astrophysics, Academia Sinica (TW)
- University of Copenhagen (DK)
- University of Milan (IT)
- Venue
- Astronomy & Astrophysics
- Publisher
- EDP Sciences
- Published
- 2022-12
- Volume
- 668
- Pages
- A162
- ISSN
- 0004-6361 (ISSN-L)
- 1432-0746
- OpenAlex
- W4308532634
- Cited by
- 20
- References
- 3
- Citations by year
- 2026: 3 · 2025: 3 · 2024: 9 · 2023: 3 · 2022: 2
- FWCI
- 1.60
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- Locations
- Astronomy and Astrophysics (publishedVersion, cc-by)
- Research at the University of Copenhagen (University of Copenhagen) (publishedVersion, cc-by)
- arXiv (Cornell University) (submittedVersion)
- Archivio Istituzionale della Ricerca (Universita Degli Studi Di Milano) (submittedVersion, cc-by)
- Springer Link (Chiba Institute of Technology) (submittedVersion)
- mediaTUM (Technical University of Munich) (submittedVersion, other-oa)
- arXiv (Cornell University)
- Funders
- National Aeronautics and Space Administration (NAS 526555)
- Space Telescope Science Institute (NAS5- 26555, 5-26555, 26555)
- Deutsche Forschungsgemeinschaft (EXC 2094, 390783311)
- Max-Planck-Gesellschaft
- Topics
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Galaxies: Formation, Evolution, Phenomena
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Astrophysical Phenomena and Observations
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Cosmology and Gravitation Theories
- Keywords
- strong gravitational lensing, dark matter distribution, brightest group galaxies, stellar kinematics, mass profiles, fossil groups, early-type galaxies, lensed arcs
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