Galaxy Clusters and Their Outskirts: the “Red Sequence”, Star Formation Rate, Stellar Mass

Resumo

We study the nearest outskirts (R < 3R_200c) of 40 groups and clusters of galaxies of the local Universe (0.02 < z < 0.045 and 300 km s^-1 < σ < 950 km s^-1). Using the SDSS DR10 catalog data, we determined the stellar mass of galaxy clusters corresponding to K_s-luminosity (which we determined earlier based on the 2MASX catalog data) (M*/M_⊙) ∝ (L_K/L⊙)^1.010±0.004 (MK < - 21^m.5, R < R_200c). We also found the dependence of the galaxy cluster stellar mass on halo mass: (M*/M_⊙) ∝ (M_200c/M_⊙)^0.77±0.01. Our results show that the fraction of galaxies with quenched star formation (M_K < -21^m) is maximal in the central regions of the galaxy clusters and equals, on the average, 0.81 ± 0.02; it decreases to 0.44 ± 0.02 outside of the projected radius R_sp (2 < R/R_200c < 3), which we found from the observed profile, but still remains higher than that in the field by 27%. The fraction of early-type “red sequence” galaxies decreases from 0.54 ± 0.02 in the center to 0.24 ± 0.01 beyond R_sp, reaching its field value.