Ram pressure statistics for bent tail radio galaxies

Abstract

In this paper,we use the MareNostrum Universe Simulation, a large-scale, hydrodynamic, nonradiative 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 ≥1011 h-1M⊙ 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 1014.5 h-1M⊙ 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 ≤ 1014 h-1M⊙, RPEX galaxies are confined to the central 500 h-1 kpc whereas in clusters of ≥1015 h-1M⊙ they can be found at distances up to 1.5 h-1 Mpc. Only clusters with masses ≥1015 h-1M⊙ are likely to host more than one BRS. Both criteria may prove useful in the search for distant, high-mass clusters.