A new classification scheme for galactic bulge X-ray sources

Observations made by ANS have been used to study the X-ray spectra of 19 strong galactic bulge sources. Eight of these objects favor an exponential-type spectrum. Spectra of the counterparts of 5 X-ray bursters also show complex, possibly thermal, spectra. Iron line emission has been discovered in 8 of these same sources while upper limits are given for 7 more sources. An under-abundance of iron relative to the cosmic value may be implied for these sources. Based on these observations, a new classification scheme is proposed for galactic bulge sources according to their spectral and temporal variations. It is found that the bulge sources exhibit an intensity-temperature relation similar to Sco X-1 (Class 1 GX source), while others, including the counterparts of several X-ray burst sources, are more like Cyg X-1 in their spectral variability (Class 2 GX sources).