Merger of massive galaxy cluster CL0238.3+2005 at z~0.4: just after pericenter passage?

Abstract

Massive clusters of galaxies are very rare in the observable Universe. Even rarer are mergers of such clusters observed close to pericenter passage. Here, we report on one such case: a massive (~ $10^{15}{M}_{\odot }$) and hot (kT ~ 10 keV) cluster CL0238.3+2005 at $z\approx 0.42$. For this cluster, we combine X-ray data from SRG/eROSITA and Chandra, optical images from DESI, and spectroscopy from BTA and RTT-150 telescopes. The X-ray and optical morphologies suggest an ongoing merger with the projected separation of subhalos of $\sim 200$ kpc. The line-of-sight velocity of galaxies tentatively associated with the two merging halos differs by 2000-3000 km/s. We conclude that, most plausibly, the merger axis is neither close to the line of sight nor to the sky plane. We compare CL0238 with two well-known clusters MACS0416 and 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 has recently (only $\lesssim 0.1$ 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, 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 intracluster medium that are associated with shock waves, e.g., electron-ion equilibration efficiency and relativistic particle acceleration.

submitted to A&A; comments are welcome

References in corpus (28)

• The eROSITA X-ray telescope on SRG
• Constraints on the Self-Interaction Cross-Section of Dark Matter from Numerical Simulations of the Merging Galaxy Cluster 1E 0657-5
• Shocks and cold fronts in galaxy clusters
• Diffuse Radio Emission from Galaxy Clusters
• The SRG X-ray orbital observatory, its telescopes and first scientific results
• Virial Scaling of Massive Dark Matter Halos: Why Clusters Prefer a High Normalization Cosmology
• The Rapid ASKAP Continuum Survey I: Design and First Results
• The speed of the `bullet' in the merging galaxy cluster 1E0657-56
• The impact of mergers on relaxed X-ray clusters - II. Effects on global X-ray and SZ properties and their scaling relations
• UNCOVER: Illuminating the Early Universe -- JWST/NIRSpec Confirmation of $z>12$ Galaxies
• Hubble Frontier Fields: The Geometry and Dynamics of the Massive Galaxy Cluster Merger MACSJ0416.1-2403
• Arc sensitivity to cluster ellipticity, asymmetries and substructures
• How Rare is the Bullet Cluster?
• A New Force in the Dark Sector?
• Free Form Lensing Implications for the Collision of Dark Matter and Gas in the Frontier Fields Cluster MACSJ0416.1-2403
• The Impact of Galaxy Cluster Mergers on Cosmological Parameter Estimation from Surveys of the Sunyaev-Zel'dovich Effect
• Tempestuous life beyond R_500: X-ray view on the Coma cluster with SRG/eROSITA. I. X-ray morphology, recent merger, and radio halo connection
• Cosmography with Supernova Refsdal through time-delay cluster lensing: independent measurements of the Hubble constant and geometry of the Universe
• The strongest gravitational lenses: I. The statistical impact of cluster mergers
• The Magnificent Five Images of Supernova Refsdal: Time Delay and Magnification Measurements
• ComPRASS: a Combined Planck-RASS catalogue of X-ray-SZ clusters
• A New Class of X-Ray Tails of Early-Type Galaxies and Subclusters in Galaxy Clusters - Slingshot Tails vs Ram Pressure Stripped Tails
• A Line-Of-Sight Galaxy Cluster Collision: Simulated X-Ray Observations
• SRG/eROSITA discovery of a radio faint X-ray candidate supernova remnant SRGe J003602.3+605421=G121.1-1.9
• The role of baryons in self-interacting dark matter mergers
• Merging galaxy clusters in IllustrisTNG
• Polarization of Sunyaev-Zeldovich signal due to electron pressure anisotropy in galaxy clusters
• Optical Identification and Spectroscopic Redshift Measurements of 216 Galaxy Clusters from the SRG/eROSITA All-Sky Survey