Origin of High X-Ray Luminosities in Optically Passive Galaxies and Resolving the Source of X-Rays in IC1613

This report covers progress of both the 'Origin of High X-ray Luminosities in Optically Passive Galaxies' and 'Resolving the Source of X-rays in IC1613' programs.The basis for the first program was our discovery in a sample of radio-selected Einstein sources of a class of galaxies which have X-ray luminosities in excess of 10⁴³ erg/s and yet give no sign whatsoever in their optical spectra that they harbor active galactic nuclei (AGN). The three brightest X-ray sources were chosen for inclusion in this program. All three fields contain several detected X-ray sources, and in at least two of the cases, the target appears to have been detected (the third case is unclear, as the object first detected with Einstein may be extended). We are attempting to identify all sources in the fields in order to estimate the astrometric offset of the ROSAT coordinate system in each field, as this is crucial to determining whether or not the source in question is coincident with the nucleus of the apparent host galaxy. With regards to the second program, IC1613 is the only dwarf galaxy in which a strong X-ray source was detected in the Einstein survey of the Local Group. Analysis with the flat-fielded data derived from the Columbia Einstein processing system suggested that the source was extended. In addition, T. Lozinskya pointed out that the source was located close to the most luminous Oxygen Wolf-Rayet star in the Local Group, suggesting the possibility that the X-rays originated in the hot cavity evacuated by the high-velocity stellar wind emanating from this star. The HRI observation was scheduled to determine the precise location and extent of the X-ray source and, in doing so, to understand its relationship to the ongoing star formation activity in this galaxy. The second brightest source in the HRI image lies in a region of active star formation in the galaxy. The source turns out to be coincident with a radio-bright supernova remnant in IC1613.