The Dependence Of Satellite Kinematics On Satellite Properties

According to the modern galaxy formation theory,galaxies are formed in dark mat-ter haloes,the properties of dark matter haloes have leading influence on galaxy forma-tion and evolution.This paper studies the dependence of satellite kinematics on satellite properties in detail,based upon SDSS Data.Satellite kinematics is an important method to measure halo mass.We assume a one-to-one relation between host galaxy mass and velocity dispersion of satellite galaxies,and use a kind of self-adapted method to choose hosts and satellites from galaxy sample.Then we study the relation between host mass and velocity dispersion of its satellites,and the relation between velocity dispersion and host properties(color and concentration)or satellite properties(mass,color,concentration and distance to its host).As before,velocity dispersion increases as host mass increas-es.In general,velocity dispersions of red(early type)host clusters are larger than blue(late type)host clusters.Around red(early type)hosts,there is no obvious connection between velocity dispersions of satellites and their masses,however,around blue(late type)hosts,massive satellites have larger velocity dispersions;red satellites have larg-er velocity dispersions than blue satellites;there is no significant difference in veloci-ty dispersions between early type satellites and late type ones;around red(early type)hosts,satellites of short distances to their hosts have larger velocity dispersions,but we don't find similar trend around blue(late type)hosts.In all,the relation between satellite properties and their velocity dispersions is relatively weak.There are two possible ex-planations of this relation,one possibility is,satellite properties relate to halo mass;while another possibility shows that satellite properties are independent of halo mass,but re-late to satellite kinematics directly.In order to distinguish these two possibilities,we ex-tract one kind of special clusters.Each of these clusters contains satellites of two cor-responding types simultaneously,so that the effect of different halo masses can be e-liminated effectively.In these special clusters we found that,no matter what properties hosts have,velocity dispersions of satellites are independent of their masses,but relate to their positions weakly,satellites of short distances to their hosts have larger veloci-ty dispersions.Red satellites have smaller velocity dispersions than blue ones,which is opposite to the result of the whole sample.These red satellites are more massive than blue ones,and have shorter distances to hosts,which indicates some complicate physi-cal processes.After wiping out these special clusters,we also study satellite kinematics of clusters which only contain some kind of satellites.We found that no matter what properties hosts have,more massive satellites have larger velocity dispersions,and this trend is more obvious than the whole sample.Similarly,red satellites have larger veloc-ity dispersions than blue satellites.Because red satellites are more massive than blue ones statistically,the dependence of velocity dispersions of satellites on their colors and masses may be consistent essentially This strongly shows a systematic relation between halo mass and satellite mass after confirming host properties,more massive satellites are in more massive haloes.It is thus clear that satellite mass is also an important factor to influence halo mass.