Ram Pressure Statistics for Bent Tail Radio Galaxies

In this paper, we use the MareNostrum Universe Simulation, a large-scale, hydrodynamic, non-radiative simulation in combination with a simple abundance matching approach to determine the ram pressure statistics for bent radio sources (BRSs). The abundance matching approach allows us to determine the locations of all galaxies with stellar masses >= 10(11) h(-1) M-circle dot in the simulation volume. Assuming that ram pressure exceeding a critical value causes bent morphology, we compute the ratio of all galaxies exceeding the ram pressure limit (RPEX galaxies) relative to all galaxies in our sample. According to our model 50 per cent of the RPEX galaxies at z = 0 are found in clusters with masses larger than 10(14.5) h(-1) M-circle dot the other half resides in lower mass clusters. Therefore, the appearance of bent tail morphology alone does not put tight constraints on the host cluster mass. In low-mass clusters, M <= 10(14) h(-1) M-circle dot, RPEX galaxies are confined to the central 500 h(-1) kpc whereas in clusters of >= 10(15) h(-1) M-circle dot they can be found at distances up to 1.5 h(-1) Mpc. Only clusters with masses >= 10(15) h(-1) M-circle dot are likely to host more than one BRS. Both criteria may prove useful in the search for distant, high-mass clusters.