Galaxy cluster A2142: halo boundary, `red sequence', properties of galaxies according to SDSS

TL;DR

This study analyzes galaxy dynamics and properties in cluster A2142 using SDSS data, identifying the halo boundary, distribution of galaxy types, and star formation activity, revealing environmental effects on galaxy evolution.

Contribution

It provides new measurements of the halo boundary, the splashback radius, and details the distribution and quenching of galaxies within and beyond the cluster in A2142.

Findings

Halo boundary (splashback radius) at ~4.1 Mpc identified.

Approximately one third of galaxies have quenched star formation.

Quenched galaxy fraction beyond splashback radius matches field values.

Abstract

The paper presents the results of studying the dynamics of galaxies, properties of early-type galaxies, properties of galaxies with the quenched star formation (QGs) in the A 2142 based on the archival data from the Sloan Digital Sky Survey. We found the observed halo boundary, the splashback radius $R_{sp}$, which is equal to 4.12 Mpc ($M_r < -20\,.\!\!^{\rm m}3$) and 4.06 Mpc ($M_r < -21\,.\!\!^{\rm m}3$) over the integral distribution of the number of galaxies as a function of the squared distance from the center. We have studied how early-type galaxies are distributed in the center and in the outskirts of the cluster ($R/R_{200}$ < 3, $M_r < -20\,.\!\!^{\rm m}3$) and plotted the red sequence in the form of (g - r) = $(-0.024\pm0.001)M_r + (0.441\pm0.005$). Among all the cluster galaxies, the galaxies with the quenched star formation ( $- 12\,yr^{- 1} < \log sSFR < - 10.75\,yr^{- 1}$) make up about one third. We have found that the fraction of QGs beyond the splashback $R_{sp}$ is the same as in the field at the same z with coordinates of the center of $16\,.\!\!^{\rm h}5$, $31^{\circ}$ and a size of $300'$. For galaxies with the stellar masses $\log M_*/M_{\odot}$ = [10.5;11.0] (this is the main mass range of QGs), after entering the cluster, there is a decrease in the radii $R_{90,r}$ by about 30\% when moving towards the center.