Galaxy Peculiar Velocities and Infall onto Groups

M. L. Ceccarelli, C. Valotto, D. G. Lambas, N. Padilla, R. Giovanelli, M. Haynes
2005 Astrophysical Journal  
We perform statistical analyses to study the infall of galaxies onto groups and clusters in the nearby Universe. The study is based on the UZC and SSRS2 group catalogs and peculiar velocity samples. We find a clear signature of infall of galaxies onto groups over a wide range of scales 5 h^-1 Mpc10^13 M_ a larger infall is observed, V_infall≃ 200 km s^-1. Similarly, we find that galaxies surrounding groups with L_g<10^15 L_ have V_infall≃ 100 km s^-1, whereas for L_g>10^15 L_ groups, the
more » ... de of the galaxy infall can be as large as V_infall≃ 250 km s^-1. The observational results are compared with the results obtained from mock group and galaxy samples constructed from numerical simulations, which include galaxy formation through semianalytical models. We obtain a general agreement between the results from the mock catalogs and the observations. The infall of galaxies onto groups is suitably reproduced in the simulations and, as in the observations, larger virial mass and luminosity groups exhibit the largest galaxy infall amplitudes. We derive estimates of the integrated mass overdensities associated with groups by applying linear theory to the infall velocities after correcting for the effects of distance uncertainties obtained using the mock catalogs. The resulting overdensities are consistent with a power law with δ∼ 1 at r ∼ 10 h^-1Mpc.
doi:10.1086/428107 fatcat:7k6bqymqjvfl7mhpyirvdorsiu