Luminosity function of faint Galactic sources in the Chandra bulge field
  We study the statistical properties of faint X-ray sources detected in the
Chandra Bulge Field. The unprecedented sensitivity of the Chandra observations
allows us to probe the population of faint Galactic X-ray sources down to
luminosities L(2-10 keV)~1e30 erg/sec at the Galactic Center distance. We show
that the luminosity function of these CBF sources agrees well with the
luminosity function of sources in the Solar vicinity (Sazonov et al. 2006). The
cumulative luminosity density of sources detected in the CBF in the luminosity
range 1e30-1e32 erg/sec per unit stellar mass is L(2-10 keV)/M*=(1.7+/-0.3)e27
erg/sec/Msun. Taking into account sources in the luminosity range 1e32-1e34
erg/sec from Sazonov et al. (2006), the cumulative luminosity density in the
broad luminosity range 1e30-1e34 erg/sec becomes L(2-10 keV)/M*=(2.4+/-0.4)e27
erg/sec/Msun. The majority of sources with the faintest luminosities should be
active binary stars with hot coronae based on the available luminosity function
of X-ray sources in the Solar environment.
