Suzaku observations of low surface brightness cluster Abell 1631

PASJ: Publications of the Astronomical Society of Japan

Mitsuishi, Ikuyuki¹  Babazaki, Yasunori¹  Ota, Naomi²  Sasaki, Shin³  Pratt, Gabriel W⁴  Böhringer, Hans⁵  Chon, Gayoung⁵  Matsumoto, Hironori⁶ 

[1] Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan;Department of Physics, Nara Women’s University, Kitauoyanishi-machi, Nara, Nara 630-8506, Japan;Department of Physics, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan;IRFU, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France;Max-Planck-Institut für extraterrestrische Physik, D-85748 Garching, Germany;Université Paris Diderot, AIM, Sorbonne Paris Cité, CEA, CNRS, F-91191 Gif-sur-Yvette, France

关键词: galaxies: clusters: individual;    galaxies: clusters: intracluster medium;    X-rays: galaxies: clusters;   

DOI  :  10.1093/pasj/psy036

学科分类：天文学(综合)

来源: Oxford University Press

【 摘 要 】

We present analysis results for a nearby galaxy cluster Abell 1631 at z = 0.046 using the X-ray observatory Suzaku. This cluster is categorized as a low X-ray surface brightness cluster. To study the dynamical state of the cluster, we conduct four-pointed Suzaku observations and investigate physical properties of the Mpc-scale hot gas associated with the A 1631 cluster for the first time. Unlike relaxed clusters, the X-ray image shows no strong peak at the center and an irregular morphology. We perform spectral analysis and investigate the radial profiles of the gas temperature, density, and entropy out to approximately 1.5 Mpc in the east, north, west, and south directions by combining with the XMM-Newton data archive. The measured gas density in the central region is relatively low (a few ×10−4 cm−3) at the given temperature (∼2.9 keV) compared with X-ray-selected clusters. The entropy profile and value within the central region (r < 0.1 r200) are found to be flatter and higher (≳400 keV cm2). The observed bolometric luminosity is approximately three times lower than that expected from the luminosity–temperature relation in previous studies of relaxed clusters. These features are also observed in another low surface brightness cluster, Abell 76. The spatial distributions of galaxies and the hot gas appear to be different. The X-ray luminosity is relatively lower than that expected from the velocity dispersion. A post-merger scenario may explain the observed results.

【 授权许可】

CC BY