Surveys of Globular Cluster and Galactic Plane X-Ray Sources.

The capabilities of the Einstein X-ray Observatory, especially the arcsecond resolution of the High Resolution Imager and the sensitivity of the Imaging Proportional Counter, have been utilized to study galactic x-ray sources. Ten previously unidentified galactic bulge x-ray sources have been observed with the HRI and located to (TURN)3'' (90% confidence radius). A diffuse infrared sources surrounding the burster GX354-0 (= MXB1728-34) has been discovered in JHK photometry. It is identified as the most heavily obscured globular cluster yet found. X -ray observations of a single burst imply that the luminosity exceeded the Eddington limit by >(, )8 times. The other nine bulge sources do not lie in obscured globular clusters. No infrared counterparts were detected for these nine sources and the limits derived are consistent with these sources being low mass x-ray binaries similar to Sco X-1. An x-ray survey of 71 galactic globular clusters has been conducted with the HRI and the IPC. Fourteen new x-ray sources with L(,x(, ))<(, )10('34.5) erg s(' -1) have been discovered in seven globular clusters; this brings to 18 the total number of known x-ray emitting globular clusters in the Galaxy. The maximum likelihood luminosity function has been derived for globular cluster x-ray sources. It is bimodal, showing two distinct classes of globular cluster x-ray sources. The dim sources, with L(,x(, ))<(, )10('34.5) erg s('-1), are identified here as binary systems containing an accreting white dwarf. An extrapolation of the x-ray luminosity function to cataclysmic variable luminosities (L(,x) (TURNEQ) 10('31) erg s('-1)) indicates that a typical globular cluster contains (TURN)10('1.3) white dwarf binaries. The IPC has been used to conduct a flux-limited survey of the galactic plane ((VBAR)b(VBAR) < 15(DEGREES)). A Galactic Plane X-ray Catalogue is presented containing the 280 x-ray sources discovered. The number-flux relation for faint galactic plane sources has a slope of -1.10 (+OR -) .16. A statistical analysis of the GPX catalogue indicates that (TURN)23% of the sources are neither extragalactic in origin nor coronal emission from non-degenerate stars. They are probably accreting white dwarfs, either low x-ray luminosity systems (e.g. cataclysmic variables) or moderate x-ray luminosity systems (e.g. the dim globular cluster sources).