Special Universe Talk: The dynamics of galaxy clusters from the CLASH-VLT survey

by Andrea Biviano (INAF/Osservatorio Astronomico di Trieste; Cluster guest)

Tuesday 28 Jul 2015, 14:00 → 15:00 Europe/Berlin

New seminar room, downstairs (MPI for Extraterrestrial Physics (MPE), Giessenbachstr., Garching)

CLASH-VLT is a VIMOS Large Programme (PI: P. Rosati, Univ. Ferrara) that builds on the CLASH HST multi-cycle treasury programme to carry out a comprehensive spectroscopic campaign on 13 massive galaxy clusters at a median redshift of 0.4. Upon completion, it will provide spectra and redshifts for ~7000 cluster members. Andrea will describe some of the results obtained with the CLASH-VLT data obtained and reduced so far. In particular, he will concentrate on the internal dynamics of galaxy clusters, as traced by cluster member galaxies. He will show that with 500 cluster members they constrain the cluster mass profile to a level of precision comparable to that obtained with gravitational lensing. This is now possible, for the first time, also for merging clusters, by going beyond the unimodal solution of the Jeans equation. Andrea will also present constraints on the orbits of galaxies in clusters, and, for the first time, on Q(r), the pseudo-phase-space density profile. Q(r) is believed to be a powerful tool to constrain the mechanisms of formation and evolution of clusters. By comparing the cluster total mass-density profile and the stellar-mass and number density profiles of cluster galaxies, they probe evolutionary mechanisms of galaxies in clusters. By comparing the kinematic and lensing determinations of cluster mass profiles, they directly probe the equation of state of dark matter. At the end of his talk Andrea will discuss future developments of this research that they will address once the CLASH-VLT data sample will be finalized.