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Precise Mass Determination of SPT-CL J2106-5844, the Most Massive Cluster at z > 1
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2020.04.09
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김진협
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Title: Precise Mass Determination of SPT-CL J2106-5844, the Most Massive Cluster at z > 1

국문제목: z > 1에서 가장 무거운 은하단 SPT-CL J2106-5844의 정밀한 질량 결정


Authors: Jinhyub Kim, M. James Jee, Saul Perlmutter, Brian Hayden, Davis Rubin, Xiaosheng Huang, Greg Aldering, and Jongwan Ko

Publication: The Astrophysical Journal, Volume 887, 2019 December


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Abstract:

We present a detailed high-resolution weak-lensing study of SPT-CL J2106-5844 at z = 1.132, claimed to be the most massive system discovered at z > 1 in the South Pole Telescope Sunyaev-Zel’dovich survey. Based on the deep imaging data from the Advanced Camera for Surveys and Wide Field Camera 3 on board the Hubble Space Telescope, we find that the cluster mass distribution is asymmetric, composed of a main clump and a subclump ∼640 kpc west thereof. The central clump is further resolved into two smaller northwestern and southeastern substructures separated by ∼150 kpc. We show that this rather complex mass distribution is more consistent with the cluster galaxy distribution than a unimodal distribution as previously presented. The northwestern substructure coincides with the brightest cluster galaxy and the X-ray peak while the southeastern one agrees with the location of the peak in number density. These morphological features and the comparison with the X-ray emission suggest that the cluster might be a merging system. We estimate the virial mass of the cluster to be ${M}_{200c}=({10.4}_{-3.0}^{+3.3}\pm 1.0)\times $ ${10}^{14}\,{M}_{\odot }$, where the second error bar is the systematic uncertainty. Our result confirms that the cluster SPT-CL J2106-5844 is indeed the most massive cluster at z > 1 known to date. We demonstrate the robustness of this mass estimate by performing a number of tests with different assumptions on the centroids, mass─concentration relations, and sample variance.