Source identification for the Swift-BAT 150-month hard X-ray catalog using soft X-ray observations

We present a comprehensive catalog of 251 potential counterparts for 250 unassociated hard X-ray sources detected in the -Burst Alert Telescope (BAT) 150-month hard X-ray survey. During 150 months of observation, BAT detected 2339 sources in the 15-150 keV range. Among these, 344 do not have a low-energy counterpart. Our study focuses on the analysis of soft X-ray observations (i.e., at energies $<$10 keV) spatially overlapping with these -BAT new hard X-ray sources. These observations were taken with , , , and . Within the sample of 251 potential counterparts, 94 (37%) are identified as active galactic nuclei (AGN) and 58 (23%) as galaxies. The rest of the 99 sources (40%) include pulsars, cataclysmic variables, and unclassified soft X-ray (0.5--10 keV) counterparts. Redshift data is available for 139 out of the 251 sources, and its distribution are in close agreement with the redshift distribution of previous BAT catalogs. We also present the results of a small optical spectroscopy campaign of 9 of the 58 galaxies. The majority of these turned out to be Seyfert 2 galaxies at a redshift slightly higher than the median of the BAT AGN sample. Swift Swift Chandra Swift-XRT eROSITA XMM-Newton