Multiwavelength Analysis of the Merging Galaxy Cluster A115
Abstract
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 {M}200={1.58}-0.49+0.56× {10}14 {M}⊙ and {3.15}-0.71+0.79× {10}14 {M}⊙ , respectively. Combining the two halos, we estimate the total cluster mass to be {M}200={6.41}-1.04+1.08× {10}14 {M}⊙ at {R}200={1.67}-0.09+0.10 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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2019
- DOI:
- 10.3847/1538-4357/ab0d7c
- arXiv:
- arXiv:1812.08797
- Bibcode:
- 2019ApJ...874..143K
- Keywords:
-
- cosmological parameters;
- cosmology: observations;
- dark matter;
- gravitational lensing: weak;
- large-scale structure of universe;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 20 pages, 17 figures, Accepted for publication in ApJ