Morphology and spectroscopy of hot gas in some early type galaxies

Abstract

We present results of morphological and spectroscopic study of hot gas in some early-type galaxies based on the analysis of high resolution X-ray images acquired from the archive of Chandra space mission. Distribution of the hot gas in target galaxies after eliminating contribution from the discrete sources (LMXBs) displays varied morphologies, ranging from very compact nuclear emission to very extensive emission, larger than even optical images of the host galaxies. The surface brightness profile of the hot gas in program galaxies is well described by a single beta model, while spectrum of the diffuse emission is best fitted by a combined soft MEKAL model and a hard power law model. We use these results to derive temperature and abundance profiles of the hot gas in host galaxies. The deprojection of the diffuse emission shows a temperature gradient in some of the galaxies. We also report on the 2-D distribution of the discrete sources (LMXBs) in host galaxies and compare it with their optical morphologies. The X-ray spectrum of the resolved sources is well-fit by a hard power law model with X-ray luminosities (0.3 to 10 keV) in the range from 5$\times$ 10$^{37}$ to 2.5$\times$ 10$^{39}$ erg s$^{-1}$. X-ray luminosity function (XLF) of the LMXBs shows a break near the luminosity comparable to the Eddington luminosity for a 1.4 M$_\odot$ neutron star.