Open AccessX‐ray emission properties of galaxies in Abell 3128
Author(s) -
Smith Russell J.
Publication year - 2003
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2003.06963.x
Subject(s) - physics , astrophysics , galaxy cluster , galaxy , astronomy , elliptical galaxy , brightest cluster galaxy , flux (metallurgy) , intracluster medium , population , active galactic nucleus , cluster (spacecraft) , luminous infrared galaxy , galaxy group , observatory , materials science , demography , sociology , computer science , metallurgy , programming language
We use archival Chandra X‐Ray Observatory data to investigate X‐ray emission from early‐type galaxies in the rich z = 0.06 cluster Abell 3128. By combining the X‐ray count rates from an input list of optically selected galaxies, we obtain a statistical detection of X‐ray flux, unbiased by X‐ray selection limits. Using 87 galaxies with reliable Chandra data, X‐ray emission is detected for galaxies down to M B ≈−19.0 , with only an upper limit determined for galaxies at M B ≈−18.3 . The ratio of X‐ray to optical luminosities is consistent with recent determinations of the low‐mass X‐ray binary content of nearby elliptical galaxies. Taken individually, in contrast, we detect significant (3σ) flux for only six galaxies. Of these, one is a foreground galaxy, whereas two are optically faint galaxies with X‐ray hardness ratios characteristic of active galactic nuclei. The remaining three detected galaxies are amongst the optically brightest cluster members, and have softer X‐ray spectra. Their X‐ray flux is higher than that expected from X‐ray binaries, by a factor of 2–10; the excess suggests that these galaxies have retained their hot gaseous haloes. The source with the highest L X / L B ratio is of unusual optical morphology with prominent sharp‐edged shells. Notwithstanding these few exceptions, the cluster population overall exhibits X‐ray properties consistent with its emission being dominated by X‐ray binaries. We conclude that in rich cluster environments, interaction with the ambient intracluster medium acts to strip most galaxies of their hot halo gas.