Galaxy clusters and their outskirts: the "red sequence", star formation rate, stellar mass

TL;DR

This study analyzes the outskirts of galaxy clusters, examining stellar mass, star formation quenching, and galaxy types, revealing radial dependencies and differences between cluster centers and the field.

Contribution

It provides new empirical measurements of stellar mass relations and star formation quenching profiles in galaxy cluster outskirts using SDSS data.

Findings

Quenched galaxy fraction is highest in cluster centers (81%) and decreases outward.

Stellar mass correlates strongly with K-band luminosity and halo mass.

Red sequence galaxy fraction drops from 54% in centers to 24% in outskirts.

Abstract

We study the outskirts ($R<3R_{200c}$) of 40 groups and clusters of galaxies of the local Universe ($0.02<z<0.045$) with 300~km~s$^{-1}<\sigma<950$~km~s$^{-1}$. Using the SDSS DR10 catalog data, we measured the stellar mass of galaxy clusters in accordance with the previously determined $K_s$-luminosity (2MASX data) and found their correlation in the form $M_*/M_{\odot} \propto (L_K/L_{\odot})^{1.010\pm0.004}$ ($M_K<-21\,.\!\!^{\rm m}5$, $R<R_{200c}$). We also found the dependence of the galaxy cluster stellar mass on halo mass: $M_*/M_{\odot} \propto (M_{200c}/M_{\odot})^{0.77\pm0.01}$}. Our results show that the fraction of galaxies with quenched star formation ($M_K<-21\,.\!\!^{\rm m}5$) is maximal in the central regions of the galaxy clusters and equals, on the average, $0.81\pm0.02$; it decreases to $0.44\pm0.02$ 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 $0.54\pm0.02$ in the center to $0.24\pm0.01$ beyond $R_{\rm sp}$, reaching its field value.