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 L2-10 keV similar to 10(30) erg s(-1) at the Galactic Centre distance. We show that the luminosity function of these CBF sources agrees well with the luminosity function of sources in the solar vicinity. The cumulative luminosity density of sources detected in the CBF in the luminosity range 10(30)-10(32) erg s(-1) per unit stellar mass is L2-10 keV/M-* = (1.7 +/- 0.3) x 10(27) erg s(-1) M-circle dot(-1). Taking into account sources in the luminosity range 10(32)-10(34) erg s-1 from Sazonov et al. 2006, the cumulative luminosity density in the broad luminosity range 10(30)-10(34) erg s(-1) becomes L2-10 keV/M-* =(2.4 +/- 0.4) x 10(27) erg s(-1) M-circle dot(-1). 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.