Multiwavelength Analysis of the Merging Galaxy Cluster A115

Mincheol Kim, M. James Jee, Kyle Finner, Nathan Golovich, David M. Wittman, R. J.Van Weeren, W. A. Dawson

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8 Citations (Scopus)


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 +0.56 -0.49 × 10 14 M and 3.15 +0.79 -0.71 × 10 14 M , respectively. Combining the two halos, we estimate the total cluster mass to be M 200 = 6.41 +1.08 -1.04 × 10 14 M at R 200 = 1.67 +0.10 -0.09 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.

Original languageEnglish
Article number143
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 2019 Apr 1

Bibliographical note

Publisher Copyright:
© 2019. The American Astronomical Society. All rights reserved.

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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