Luminosity Function of X-ray Sources in Globular Clusters
Abstract
We have analyzed the X-ray luminosity functions(LFs)of cataclysmic variables (CVs) and active binaries(ABs) for four Galactic globular clusters(GCs), down to the detection thresholds of the archival Chandra observations. The X-ray source samples used exclude those identified millisecond pulsars, quiescent low-mass X-ray binaries, and interloper stars, individually, as well as the background AGN contributions, statistically. We have also corrected for the detection incompleteness and Eddington bias in the LF construction. The LFs of the four GCs are consistent with each other, except for Omega-Centauri, which shows a relatively low source density per unit mass. We then compare the LFs with the field population. The LFs of the GCs appear substantially flatter than that of the field. The GCs thus seem to harbor more luminous sources and less dim ones than the field does. We will discuss implications of these findings on the dynamic formation and evolution of CVs and ABs, as well as their progenitor stars, in the GCs.
- Publication:
-
AAS/High Energy Astrophysics Division #12
- Pub Date:
- September 2011
- Bibcode:
- 2011HEAD...12.1317X