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Multiwavelength Analysis of Two New Dissociative Galaxy Cluster Mergers

Presentation #139.18 in the session Galaxy Clusters/Large Scale Structure, Cosmic Distance — iPoster Session.

Published onJun 29, 2022
Multiwavelength Analysis of Two New Dissociative Galaxy Cluster Mergers

Binary mergers of galaxy clusters are powerful tools for revealing the properties of dark matter (DM). In these mergers, colliding intra-cluster medium (ICM) particles exchange momentum and fall behind the (primarily non-collisional) galaxies. By comparing the behavior of DM halos with gas particles versus galaxies, an upper boundary on the self-interaction cross-section of dark matter can be obtained. However, only a few clean dissociative mergers have been identified so far. Finding and characterizing new systems is a necessity to accurately model such mergers and constrain dark matter parameters. In this work, we present a multiwavelength analysis of two new binary mergers — Abell 56 (z=0.3) and RM J150822.0+575515.2 (z=0.54) — identified by the merger-finding algorithm presented by Bouhrik et al. For both of these clusters, X-ray observations indicate a single-peaked distribution of the ICM gas, whereas weak-lensing maps show a bimodal mass distribution as well as a good agreement between the DM location and the galaxies seen in the optical. The offset between the X-ray and DM peaks confirms the dissociative nature of these mergers. Good relic candidates can be seen in the radio, although further observations are needed to confirm them. By characterizing the systems via state-of-the-art multiwavelength observations, we were able to select simulated analogs of the clusters in order to reconstruct their merger histories and obtain confidence intervals for parameters of interest, such as the time since pericenter, pericenter velocity, and polar viewing angle.

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