The Influence of the Dynamic State of Galaxy Clusters on Segregation Phenomena and Velocity Dispersion Profiles (1812.01095v1)

Abstract: In this work we investigate the influence of the dynamic state of galaxy clusters on segregation effects and velocity dispersion profiles (VDPs) for a sample of 111 clusters extracted from SDSS-DR7. We find that 73 clusters have Gaussian (G) velocity distribution and 38 clusters have a complex or non-Gaussian (NG) velocity distribution. We also split the G and NG samples into 'active' and 'passive' galaxies, according to their sSFRs and stellar masses. Our results indicate a strong spatial segregation between active and passive galaxies both in G and NG systems, with passive galaxies being more central. We also found that the passive population in G systems is the only family with lower velocity dispersions for the brightest galaxies ($M_r \lesssim -22.75$), thus presenting velocity segregation with luminosity. The similarity found between the VDPs of the galaxy populations in NG systems indicate that these sets probably share a similar mix of orbits. We also found a clear evolutionary trend for G systems, with brighter galaxies in richer clusters having flatter VDPs. The scenario emerging from this study suggests a direct relationship between segregation effects, VDPs and the dynamic state of clusters.