Merger Signatures in the Galaxy Cluster Abell 98
Abstract
We present results from Chandra and XMM-Newton observations of the galaxy cluster Abell 98 (A98), which shows three major components: a relatively bright subcluster to the north (A98N), a disturbed subcluster to the south (A98S), and a fainter subcluster to the far south (A98SS). We find evidence of a surface brightness and temperature asymmetry in A98N that is consistent with the presence of a leading bow shock to the south, created by an early stage merger between A98N and A98S. We also find that A98S has an asymmetric temperature structure in the core, likely due to a separate ongoing merger. Evidence for this is also seen in the optical data. A98S hosts a wide-angle tail (WAT) radio source powered by a central active galactic nucleus (AGN). We find evidence for a cavity in the intracluster medium (ICM) that has been evacuated by one of the radio lobes, suggesting that AGN feedback is operating in this system. The three main subclusters lie along a line in projection, suggesting the presence of a large scale filament. We observe an excess of emission along the filament between A98N and A98S, but a surface brightness profile shows that this excess emission is consistent with the overlap of the extended gas haloes of A98N and A98S. We find that the temperature of this region is consistent with the temperature of the gas at similar radii outside this bridge region. Lastly, we examine the cluster dynamics. We find that A98N and A98S are likely bound to one another, with a 67% probability, while A98S and A98SS are not bound at a high level of significance.
- Publication:
-
American Astronomical Society Meeting Abstracts #224
- Pub Date:
- June 2014
- Bibcode:
- 2014AAS...22422202P