The distribution of dark matter and gas spanning 6 Mpc around the post-merger galaxy cluster MS 0451-03
Abstract
Using the largest mosaic of Hubble Space Telescope images around a galaxy cluster, we map the distribution of dark matter throughout an ∼6 × 6 Mpc2 area centred on the cluster MS 0451-03 (z = 0.54, $M_{200}=1.65\times 10^{15}\, {\rm M}_{\odot }$ ). Our joint strong- and weak-lensing analysis shows three possible filaments extending from the cluster, encompassing six group-scale substructures. The dark matter distribution in the cluster core is elongated, consists of two distinct components, and is characterized by a concentration parameter of c200 = 3.79 ± 0.36. By contrast, XMM-Newton observations show the gas distribution to be more spherical, with excess entropy near the core, and a lower concentration of $c_{200}=2.35^{+0.89}_{-0.70}$ (assuming hydrostatic equilibrium). Such a configuration is predicted in simulations of major mergers 2-7 Gyr after the first core passage, when the two dark matter haloes approach second turnaround, and before their gas has relaxed. This post-merger scenario finds further support in optical spectroscopy of the cluster's member galaxies, which shows that star formation was abruptly quenched 5 Gyr ago. MS 0451-03 will be an ideal target for future studies of the growth of structure along filaments, star formation processes after a major merger, and the late-stage evolution of cluster collisions.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- August 2020
- DOI:
- 10.1093/mnras/staa1828
- arXiv:
- arXiv:2006.10156
- Bibcode:
- 2020MNRAS.496.4032T
- Keywords:
-
- galaxies: clusters: general;
- cosmology: observations;
- gravitational lensing: weak;
- large-scale structure of Universe;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 21 pages, 13 figures, updated to match MNRAS version