Observations Of X-Ray Sources In M31
L. Van Speybroeck, A. Epstein, W. Forman, R. Giacconi, C., Jones, W. Liller, L. Smarr, Astrophysical Journal Letters, 234, L45-L49 (1979).
Abstract
We have observed 69 unresolved Xray sources and seven diffuse or confused source regions in M31 with the Einstein Observatory. The typical limiting sensitivities in the 0.5-4.5keV band were 9X1036ergss-1. There are 21 sources in a compact inner bulge, seven globular clusters, 40 sources we categorize as Population I, and 8 sources near globular clusters but with position errors large enough so that four chance coincidences would be expected. The Population I sources are associated with bright visible objects and with neutral hydrogen, dust, and other Population I tracers. Luminosity distributions of these classes are given. The nucleus of M31 is coincident with a 1038ergss-1X-ray source at approximately the 90% confidence level.