Misc,
Stripping of the Hot Gas Halos in Member Galaxies of Abell 1795
(2017)cite arxiv:1711.02675Comment: Submitted to ApJ. Comments welcome.
Abstract
Combining archival Chandra X-ray Observatory and Sloan Digital Sky Survey
(SDSS) observations of the nearby cluster Abell 1795, we have compiled a sample
of 61 massive (M_star > 10^10 M_sun) cluster members spanning 0.25 < R/R_500 <
2.5 that have five bands of SDSS coverage and were observed within 5 arcmin of
the Chandra optical axis in at least one observation. The Abell 1795 cluster
members have been separated into two coarse clustercentric radius bins: 0.25 <
R/R_500 < 1 and 1 < R/R_500 < 2.5. X-ray images at 0.5-1.5 keV for each member
were created and then stacked in the two radial bins. We have defined a model
that accounts for the dominant X-ray emission expected in and around cluster
galaxies: the intracluster medium (ICM), low- and high-mass X-ray binaries,
active galactic nuclei, and hot gas halos. Surface brightness profiles of inner
and outer cluster galaxies are simultaneously fit in order to inform the
initial state of a Markov chain Monte Carlo (MCMC) sampling. The MCMC code
emcee is used to derive the best fit between the data and the model, and
generate 25 million sets of model parameters, which we use to measure the
0.5-1.5 keV luminosities of each model component. Leveraging effective total
Chandra exposure times of 3.3 and 2.1 Msec at 0.25 < R/R_500 < 1 and 1 <
R/R_500 < 2.5, respectively, we have detected hot gas halos, in a statistical
sense, around Abell 1795 cluster members. Galaxies at 1 < R/R_500 < 2.5 have
0.5-1.5 keV hot halo luminosities of log(L_X/(erg/s))=39.9+/-0.2, an order of
magnitude larger than galaxies in the inner cluster
(log(L_X/(erg/s))=38.6(+0.6)(-0.7)). This result suggests that the ICM is
removing hot gas from the halos of Abell 1795 members as they fall into the
cluster, which is strong evidence for ongoing quenching by strangulation.
