Stripping of the Hot Gas Halos in Member Galaxies of Abell 1795

TL;DR

This study investigates hot gas stripping in galaxies within Abell 1795, finding that galaxies closer to the cluster center have significantly reduced hot gas halos, indicating ram pressure stripping by the intracluster medium.

Contribution

It provides the first statistical evidence of hot gas halo stripping in cluster galaxies using deep Chandra X-ray observations and a novel stacking analysis approach.

Findings

Outer cluster galaxies have six times larger hot gas halo luminosities than inner ones.

Hot gas halos are detected around outer cluster members but are absent in inner members.

Results support ram pressure stripping of hot gas in galaxies falling into the cluster.

Abstract

The nearby cluster Abell 1795 is used as a testbed to examine whether hot gas in cluster galaxies is stripped by the ram pressure of the intracluster medium (ICM). The expected X-ray emission in and around Abell 1795 galaxies is likely dominated by the ICM, low-mass X-ray binaries, active galactic nuclei, and hot gas halos. In order to constrain these components, we use archival Chandra X-ray Observatory and Sloan Digital Sky Survey (SDSS) observations of Abell 1795 and identify 58 massive (M_star>10^10 M_sun) spectroscopic cluster members within 5 arcmin of the Chandra optical axis. X-ray images at 0.5-1.5 keV and 4-8 keV were created for each cluster member and then stacked into two clustercentric radius bins: inner (0.25<R/R_500<1) and outer (1<R/R_500<2.5). Surface brightness profiles of inner and outer cluster members are fit using Markov chain Monte Carlo sampling in order to generate model parameters and measure the 0.5-1.5 keV luminosities of each model component. Leveraging effective total Chandra exposure times of 3.4 and 1.7 Msec for inner and outer cluster members, respectively, we report the detection of hot gas halos, in a statistical sense, around outer cluster members. Outer members have 0.5-1.5 keV hot halo luminosities (L_X = 8.1(-3.5/+5)x10^39 erg/s) that are six times larger than the upper limit for inner cluster members (L_X < 1.3x10^39 erg/s). This result suggests that the ICM is removing hot gas from the halos of Abell 1795 members as they fall into the cluster.