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名稱Title
2021天文年會
國立嘉義大學蘭潭校區
5月21日至23日

論文摘要

Mass-Velocity Dispersion Relation in HIFLUGCS Galaxy Clusters

[ Oral ]

Yong Tian(Institute of Astronomy, National Central University, Taoyuan 32001, Taiwan); Po-Chieh Yu(College of General Studies, Yuan-Ze University, Taoyuan 32003, Taiwan); Pengfei Li(Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106, USA);Stacy S. McGaugh(Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106, USA); Chung-Ming Ko(Institute of Astronomy, National Central University, Taoyuan 32001, Taiwan; Department of Physics and Center for Complex Systems, National Central University, Taoyuan 32001, Taiwan)

We investigate the mass-velocity dispersion relation (MVDR) in 29 galaxy clusters in the HIghest X-ray FLUx Galaxy Cluster Sample (HIFLUGCS). We measure the spatially resolved, line-of-sight velocity dispersion profiles of these clusters, which we find to be mostly flat at large radii, reminiscent of the rotation curves of spiral galaxies. We discover a tight empirical relation between the baryonic mass Mbar and the flat velocity dispersion of the member galaxies. The residuals of the MVDR are uncorrelated with other cluster properties such as temperature, cluster radius, baryonic mass surface density, and redshift. These characteristics are reminiscent of a similar relation for galaxies, albeit about ten times larger characteristic acceleration scale. The cluster baryon fraction falls short of the cosmic value, exposing a problem: the discrepancy increases systematically for clusters of lower mass and lower baryonic acceleration.