Multiwavelength Analysis of the Merging Galaxy Cluster A115

• Published in: The Astrophysical journal Vol. 874; no. 2; pp. 143 - 160
• Main Authors: Kim, Mincheol, Jee, M. James, Finner, Kyle, Golovich, Nathan, Wittman, David M., Weeren, R. J. van, Dawson, W. A.
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 02-04-2019; IOP Publishing; Institute of Physics (IOP)
• Subjects: Astronomical models; ASTRONOMY AND ASTROPHYSICS; Astrophysics; Centroids; cosmological parameters; cosmology: observations; dark matter; Deimos; Disruption; Galactic clusters; Galaxies; Galaxy mergers & collisions; gravitational lensing: weak; Halos; large-scale structure of universe; Spectroscopy; Stars & galaxies
• ISSN: 0004-637X; 1538-4357; 1538-4357
• DOI: 10.3847/1538-4357/ab0d7c

A115 is a merging galaxy cluster at z ∼ 0.2 with a number of remarkable features, including a giant (∼2.5 Mpc) radio relic, two asymmetric X-ray peaks with trailing tails, and a peculiar line-of-sight velocity structure. We present a multiwavelength study of A115 using optical imaging data from Subaru, X-ray data from Chandra, and spectroscopic data from the Keck/DEIMOS and MMT/Hectospec instruments. Our weak-lensing (WL) analysis shows that the cluster is composed of two subclusters whose mass centroids are in excellent agreement with the two brightest cluster galaxy positions ( 10″). By modeling A115 with a superposition of two Navarro-Frenk-White halos, we determine the masses of the northern and southern subclusters to be and , respectively. Combining the two halos, we estimate the total cluster mass to be at Mpc. These WL masses are significantly (a factor of 3-10) lower than what is implied by the X-ray and optical spectroscopic data. We attribute the difference to the gravitational and hydrodynamic disruption caused by the collision between the two subclusters.