The X-ray Binary Populations of M81 and M82
Abstract
We present a detailed study of the X-ray point source populations of the nearby, star-forming, spiral galaxy M81. Using deep HST data, we uniquely classify the X-ray binary (XRB) populations on the basis of their donor stars and local stellar populations. While this analysis is focused on Chandra observations most sensitive to the central galactic regions, we also include preliminary analysis of new Chandra observations probing the outer disk regions. These new observations importantly enable us to study XRBs across the entire disk at a range of ages. We measure the X-ray luminosity functions (XLFs) of the different XRB sub-populations (early-type main sequence, supergiant, low-mass, globular cluster), and we compare these results with predictions from XRB population synthesis models. This more robust classification (than the common, simple bulge/disk spatial separations) of XRBs minimizes contamination between different sub-populations, and it shows that high-mass XRBs have steeper XLFs than the "canonical" star-forming galaxy XLF commonly used. In the case of globular clusters, we find that more massive and denser globular clusters are more likely to be associated with XRBs. We also compare these results with the XRB populations of the prototypical starburst galaxy, M82, for which we present the deepest XLF reported for a starburst galaxy. We discuss the variations of the XRB populations in regions of M82 dominated by star-formation episodes at different ages, and in the context of predictions from XRB formation and evolution models.
- Publication:
-
American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019
- Bibcode:
- 2019AAS...23326014S