Issue |
A&A
Volume 693, January 2025
|
|
---|---|---|
Article Number | A33 | |
Number of page(s) | 18 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361/202451969 | |
Published online | 23 December 2024 |
Mass and light in galaxy clusters: The case of Abell 370
1
Aix Marseille Univ., CNRS, CNES, LAM, Marseille, France
2
Institute of Physics, Laboratory of Astrophysics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Observatoire de Sauverny, 1290 Versoix, Switzerland
3
ESO, Alonso de Córdova 3107, Vitacura, Santiago, Chile
4
LPNHE, CNRS/IN2P3, Sorbonne Université, Université Paris Cité, Laboratoire de Physique Nucléaire et de Hautes Energies, 75005 Paris, France
5
Instituto de Fisica de Cantabria (CSIC-UC), Avda. Los Castros s/n, E-39005 Santander, Spain
6
Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham DH1 3LE, UK
7
Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE, UK
8
Astrophysics Research Centre, University of KwaZulu-Natal, Westville Campus, Durban 4041, South Africa
9
School of Mathematics, Statistics & Computer Science, University of KwaZulu-Natal, Westville Campus, Durban 4041, South Africa
10
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
11
Department of Astronomy, University of Michigan, 1085 S. University Ave, Ann Arbor, MI 48109, USA
12
STAR Institute, Quartier Agora, Allée du Six Août, 19c, B-4000 Liège, Belgium
13
School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
14
Université Lyon 1, CNRS, Centre de Recherche Astrophysique de Lyon (CRAL), Saint-Genis-Laval, France
15
Physics Department, Ben-Gurion University of the Negev, PO Box 653 Be’er-Sheva 84105, Israel
16
Caltech/IPAC, 1200 E. California Blvd, Pasadena, CA 91125, USA
17
Department of Astronomy/Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721, USA
18
Department of Astronomy, Yale University, PO Box 208101 New Haven CT 06520, USA
19
Department of Physics, Yale University, PO Box 208120 New Haven, CT 06520, USA
20
Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547, USA
⋆ Corresponding author; marceau.limousin@lam.fr
Received:
23
August
2024
Accepted:
25
October
2024
In the cold dark matter (CDM) paradigm, an association between the hypothetic dark matter (DM) and its stellar counterpart is expected. However, parametric strong-lensing studies of galaxy clusters often display misleading features: DM components on the group or cluster scale without any stellar counterpart, offsets between the two components that are larger than what might be allowed by CDM or self-interacting DM models, or significant unexplained external shear components. This is the case in the galaxy cluster Abell 370, whose mass distribution has been the subject of several studies that were motivated by a wealth of data. The cluster was described parametrically with strong-lensing techniques by a model with four dark matter clumps and galaxy-scale perturbers, and with a significant external shear component, whose physical origin remains a challenge. The dark matter distribution features a mass clump without a stellar counterpart and a significant offset between one of the dark matter clumps and its associated stellar counterpart. This paper is based on BUFFALO data, and we begin by revisiting this mass model. Sampling this complex parameter space with Markov chain Monte Carlo (MCMC) techniques, we find a solution that does not require any external shear and provides a slightly better root mean square (RMS) than previous models (0.7″ compared to 0.9″). Investigating this new solution further, in particular, by varying the parameters that lead the MCMC sampler, we present a class of models that can accurately reproduce the strong-lensing data, but whose parameters for the dark matter component are poorly constrained. This limits any insights into its properties. We then developed a model in which each large-scale dark matter component must be associated with a stellar counterpart. This model with three dark matter clumps cannot reproduce the observational constraints with an RMS smaller than 2.3″, and the parameters describing this dark matter component remain poorly constrained. Examining the total projected mass maps, we find a good agreement between the total mass and the stellar distribution, which are both bimodal to first order. We interpret the misleading features of the mass model with four dark matter clumps and the failure of the mass model with three dark matter clumps as being symptomatic of the lacking realism of a parametric description of the dark matter distribution in such a complex merging cluster. We encourage caution and attention on the outputs of parametric strong-lensing modelling. We briefly discuss the implications of our results for using Abell 370 as a gravitational telescope. With the class of models that reproduce the strong- lensing data, we computed the magnifications for background Lyα emitters, and we present the critical curves obtained for the redshift of the Dragon arc, whose recent observations with the James Webb Space Telescope prompted interest. Finally, in light of our results, we discuss the strategy of choosing merging (multi-modal) clusters as gravitational telescopes compared to simple (unimodal) clusters.
Key words: dark matter / large-scale structure of Universe
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This article is published in open access under the Subscribe to Open model. Subscribe to A&A to support open access publication.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.