X-ray Binaries and Their Makers
Abstract
Exploring the relations between star formation activity, stellar mass distribution and luminous X-ray binaries (XRBs) often results in considerable progress in understanding the nature, formation, and diversity of the different classes of X-ray binaries. Over the last decade, several studies have demonstrated the existence of a tight correlation between the collective number and luminosity of short-lived (< 10-50 Myr) high-mass X-ray binaries (HMXBs) as well as ultra-luminous X-ray sources (ULXs) and the integrated star formation rate (SFR) of late-type host galaxies. It is also known that the collective number and luminosity of long-lived (> 1 Gyr) low-mass X-ray binaries (LMXBs) correlate well with the integrated stellar mass of host early-type galaxies and bulges of late-type galaxies. We report on our recent results that introduce a new multi-wavelength technique to explore these correlations in greater detail. We have constructed spatially-resolved images of SFR density using combinations of Galex FUV and Spitzer 24μm images. We have also obtained stellar mass surface brightness maps using combinations of 2MASS H-band and SDSS g- and i-band images. By means of these maps we have investigated the spatial and luminosity distributions of XRBs detected with Chandra in star-forming and early-type galaxies as a function of the local SFR and stellar mass densities respectively, around the X-ray sources. This method was first applied to study the population of ULXs in the colliding galaxy pair NGC 2207/IC 2163 and the population of LMXBs in the elliptical galaxy NGC 4649. We find that the number and luminosity of both young XRBs per unit SFR and old XRBs per unit stellar mass are in agreement with those predicted by the galaxy-wide average relations. We will also report on preliminary results of an ongoing and much more extensive work in which the same method is being applied on a significantly larger number of X-ray sources detected in a sample of nearby grand-design spiral galaxies to characterize the spatial dependence of X-ray luminosity functions for the different classes of XRBs.
- Publication:
-
AAS/High Energy Astrophysics Division #13
- Pub Date:
- April 2013
- Bibcode:
- 2013HEAD...1312650M