Deep Hard X-ray Survey of the M81 Field Based on INTEGRAL1 Data

Abstract

We have carried out a deep survey of the M81 field in the 25–60 keV energy band based on long-term (2003–2023) INTEGRAL observations. A record sensitivity of 0.16 mCrab at a detection significance of \(4\sigma\) has been achieved in the central part of the field owing to the long accumulated exposure (19.2 Ms). The total area of the survey is 1004 deg\({}^{2}\) at a sensitivity level better than 0.72 mCrab. We have produced a catalog of sources detected at a significance level higher than \(4\sigma\). It contains 51 objects most of which are active galactic nuclei (AGNs). The median redshift of the Seyfert galaxies in the catalog is \(z=0.0366\). Six sources have not been detected previously in any of the X-ray surveys. According to the available indirect data, all of them and two more sources that have already been entered previously into the INTEGRAL survey catalogs can also be AGNs, including those with strong internal absorption.