Extragalactic XRB population
Abstract
XRB populations can be detected with Chandra in all types of galaxies. We can now study the energy distribution, variability, and luminosity function (XLF) of these sources, both to understand their nature and evolution in different stellar populations. XLFs differ for different types of XRBs: the HMXB XLF is a power-law extending to ULXs; the LMXB XLF presents breaks and different power-laws that can be related to the evolution of LMXBs (GC or field) and the age of the stellar population. Based on LMXB population studies in elliptical galaxies it appears that LMXBs are formed both in the field and in GCs and that a fraction of field LMXBs originates in GCs. More luminous, red, compact GCs are more likely to host X-ray sources. Spectral variability patterns of high L_{X} sources are reminiscent of BHBs, if BHBs, M_{BH}∼ 5-15 M_{⊙}. Transient high luminosity LMXBs are detected, prevalently in the field, but some are also present in GCs. There is increasing evidence of BH binaries in GCs. Finally, XRB detections with Chandra are not limited to stellar systems. Recently, a double supermassive black hole system, on its way to become a bound binary, has been detected in the Compton-thick AGN nucleus of the galaxy NGC 3393.
- Publication:
-
X-ray Binaries. Celebrating 50 Years Since the Discovery of Sco X-1
- Pub Date:
- July 2012
- Bibcode:
- 2012xrb..confE..14F