Propiedades de grupos de galaxias en la vecindad de cúmulos masivos

RAGONE, C.; MERCHÁN, M.; MURIEL, H.; ZANDIVAREZ, A.

Argentina

Congreso; 46 Reunión Anual de la Asociación Argentina de Astronomía; 2003

Asociación Argentina de Astronomía

This work analyses the  properties of groups of galaxies in thesurroundings of clusters. On the basis of a very large public Virgo Consortium  Simulation, we identified systems of galaxies in a wide range of masses. Systems with masses greater than M_cut= 4 x10^14~M_sun ~h^-1 are considered "host", whereas smaller systems are taken as groups.Our results show that groups properties are affected by the proximityof massive hosts. Physical properties such as velocity dispersion, internal energy (E) and virial radius, show an increment, whereas the mean density decreases asthe host-group distance is smaller. By analysing groups with different properties,we find that the low mass and the weakly bounded (E > 0) subsamples, are strongly affected by the presence of the host; on the other hand, massive groups and groups with E < 0do not show dependence on the host-group distance.Using a sample of groups identified in the final version of the 2dF Galaxy Redshift Survey, we find a very similar velocity dispersion behaviour in the observational data compared toresults in the simulation. We also study the dependence of the groups velocity dispersion on thehost masses in both, observations and simulation; finding thatthe larger is the host mass the higher is the effect on its vicinity.These results are discussed in the framework of the tidal forces exerted by the host massive clusters.