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 multi-wavelength 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 analysis shows that the cluster is comprised of two subclusters whose mass centroids are in excellent agreement with the two BCG 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 M200 = 1.58+0.56−0.49 × 1014M☉ and 3.15+0.79−0.71 × 1014M☉, respectively. Combining the two halos, we estimate the total cluster mass to be M200 = 6.41+1.08−1.04 × 1014M☉ at R200 = 1.67+0.10−0.09 Mpc. These weak-lensing 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 status||Published - 2018 Dec 20|
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