REVISITING WITH<i>CHANDRA</i>THE SCALING RELATIONS OF THE X-RAY EMISSION COMPONENTS (BINARIES, NUCLEI, AND HOT GAS) OF EARLY-TYPE GALAXIES

Abstract

We have selected a sample of 30 normal (non-cD) early type galaxies, for all\nof which optical spectroscopy is available, and which have been observed with\nChandra to a depth such to insure the detection of bright low-mass X-ray\nbinaries (LMXBs) with Lx&gt;1e38 erg/s. This sample includes a larger fraction of\ngas-poor galaxies than previously studied samples, and covers a wide range of\nstellar luminosity, velocity dispersion, GC specific frequency, and stellar\nage. We derive X-ray luminosities (or upper limits) from the different\nsignificant X-ray components of these galaxies: nuclei, detected and undetected\nLMXBs, coronally active binaries (ABs), cataclysmic variables (CVs), and hot\ngas. The ABs and CVs contribution is estimated from the Lx-LK scaling relation\nof M31 and M32. The contribution of undetected LMXBs is estimated both by\nfitting the spectra of the unresolved X-ray emission and by extrapolating the\nLMXB X-ray luminosity function. The results for the nuclei are consistent with\nthose discussed by Pellegrini (2010). We derive a revised scaling relation\nbetween the integrated X-ray luminosity of LMXBs in a galaxy and the LK\nluminosity of the host galaxy: Lx(LMXB)/LK ~ 1e29 erg s-1 LK-1 with 50% 1sigma\nrms; moreover, we also obtain a tighter LX(LMXB)/LK - SN relation than\npreviously published. We revisit the relations between hot gas content and\nother galaxy parameters. finding a steeper LX(gas)-LK relation with larger\nscatter than reported in the literature. We find a positive correlation between\nthe luminosity and temperature of the hot ISM, significantly tighter than\nreported by earlier studies.[abridged]\n