Final Report Summary - X-RAY-GAL (X-ray studies of nearby galaxies)
X-ray observations of nearby galaxies allow us to study: (a) the properties of their hot gas produced by the interaction between the stellar winds and supernova remnants with their surrounding interstellar gas; and (b) the discrete X-ray sources which are related to the end-points of the stellar evolution (e.g. supernova remnants and X-ray binaries).
The subject of this effort is to study the X-ray binaries in a small sample of nearby galaxies. X-ray binaries are systems consisting of a compact objects (white dwarf, neutron star, or black hole) accreting matter from a donor star. Depending on the nature of the donor star we can have high-mass X-ray binaries (HMXBs) or low mass X-ray binaries (LMXBs) if it is a massive (early-type) star or a low mass (<1 solar mass; late-type) star. Therefore, both signals to noise radio (SNRs) and X-ray binaries, provide important information on stellar evolution, particularly its end-points, and their populations reflect the star-formation history of a galaxy.
As part of this project we have analysed X-ray (Chandra) and supporting space (Hubble space telescope; HST) and ground based optical data for a set of nearby galaxies including our two nearest irregular galaxies (the small and large magellanic clouds) and one elliptical galaxy (NGC4261). For these galaxies we studied the properties of their X-ray sources, and we calculated their X-ray luminosity functions (including corrections for observational biases), and we compared them with a library of simulations in order to constrain parameters in their formation and evolution.