Mass-Velocity Dispersion Relation in HIFLUGCS Galaxy Clusters

Understand

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 galaxies.
• We discover a tight empirical relation between the baryonic mass $M_\mathrm{bar}$ and the flat velocity dispersion $\sigma$ of the member galaxies, i.e.
• MVDR, $\log(M_\mathrm{bar}/M_\odot)=4.1^{+0.4}_{-0.4}\,\log(\sigma/\mathrm{km}\,\mathrm{s}^{-1})+1.6^{+1.0}_{-1.3}$, with the lognormal intrinsic scatter of $12^{+3}_{-3}\%$.