Low-mass X-ray binaries in elliptical galaxies
Abstract
We have studied the properties of populations of low-mass X-ray binaries (LMXBs) in early-type galaxies, focusing on their environmental dependence which reveals their formation and evolution histories. Our sample includes ~30 galaxies with Chandra observations, and ~2000 LMXBs were detected in total which cover the whole luminosity range (E35 to above E39 erg/s). We found the luminosity distributions of LMXBs have a strong dependence on different stellar density (e.g. globular clusters, galactic nuclei vs. galaxy field), and velocity dispersion (globular clusters vs. galactic nuclei). And the number density of LMXBs depends on the age of the stellar population and the globular cluster content. We also found that young galaxies contain more ultraluminous X-ray sources (ULXs), which makes LMXBs the most popular explanation of ULXs found in early-type galaxies. Moreover, X-ray sources were found more extended to the outside of D25 radius of galaxies, which were assumed to be associated with globular clusters which trace the galaxy dark matter halo.
- Publication:
-
X-ray Binaries. Celebrating 50 Years Since the Discovery of Sco X-1
- Pub Date:
- July 2012
- Bibcode:
- 2012xrb..confE..67Z