The massive galaxy cluster CL0238.3+2005 (the Peanut cluster) at z = 0.42: A merger just after pericenter passage?
Year: 2024
Type: article
Abstract: Massive clusters of galaxies are very rare in the observable Universe. Mergers of such clusters observed close to pericenter passage are even rarer. Here, we report on one such case: The massive (∼1015 M⊙) and hot (kT ∼ 10 keV) cluster CL0238.3+2005 at z = 0.42. For this cluster, we combined X-ray data from SRG/eROSITA and Chandra, optical images from DESI, and spectroscopy from the BTA and RTT-150 telescopes. The X-ray and optical morphologies suggest an ongoing merger with a projected separation of the subhalos of ∼200 kpc. The line-of-sight velocity of galaxies that are tentatively associated with the two merging halos differs by 2000–3000 km s−1. We conclude that the merger axis is most likely neither close to the line of sight nor to the sky plane. We compare CL0238 with the two well-known clusters MACS0416 and the Bullet and conclude that CL0238 corresponds to an intermediate phase between the pre-merging MACS0416 cluster and the post-merger Bullet cluster. Namely, this cluster recently (only ≲0.1 Gyr ago) experienced an almost head-on merger. We argue that this “just after” system is a very rare case and an excellent target for lensing, the Sunyaev-Zeldovich effect, and X-ray studies that can constrain properties ranging from dynamics of mergers to self-interacting dark matter, and plasma effects in the intracluster medium that are associated with shock waves, for instance, electron-ion equilibration efficiency and relativistic particle acceleration.
Source: Astronomy and Astrophysics
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,732
Funders: National Science Foundation, U.S. Department of Energy, National Aeronautics and Space Administration, University of Pennsylvania, Ohio State University, California Institute of Technology, Science and Industry Endowment Fund, University of Portsmouth, Australian Government, University of Sussex, Commonwealth Scientific and Industrial Research Organisation, Chinese Academy of Sciences, Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, Government of Western Australia, Ministry of Science and Higher Education of the Russian Federation, Office of Science, Jet Propulsion Laboratory, Division of Astronomical Sciences, High Energy Physics, SLAC National Accelerator Laboratory
OpenAlex ID: W4404806753