The Chandra Large Area Synoptic X-ray Survey (CLASXS) of the Lockman Hole-Northwest: The X-ray Catalog

摘要

We present the X-ray catalog and basic results from our Chandra Large AreaSynoptic X-ray Survey (CLASXS) of the Lockman Hole-Northwest field. Our 9ACIS-I fields cover a contiguous solid angle of ~0.4 sq. deg. and reach fluxesof 5E-16 cgs (0.4-2 keV) and 3E-15 cgs (2-8keV). Our survey bridges the gapbetween ultradeep pencil-beam surveys, such as the Chandra Deep Fields (CDFs),and shallower, large area surveys, allowing a better probe of the X-ray sourcesthat contribute most of the 2-10 keV cosmic X-ray background (CXB). We find atotal of 525 X-ray point sources and 4 extended sources. At ~10E-14 cgs 2-8keV, our number counts are significantly higher than those of severalnon-contiguous, large area surveys. On the other hand, the integrated flux fromthe CLASXS field, combined with ASCA and Chandra ultradeep surveys, isconsistent with results from other large area surveys, within the variance ofthe CXB. Spectral evolution is seen in the hardening of the sources at fluxesbelow 1E-14 cgs Above 4E1-14 cgs(0.4-8 keV), ~60 of the sources are variable.Four extended sources in CLASXS is consistent with the previously measuredLogN-LogS of galaxy clusters. We report the discovery of a gravitationallensing arc associated with one of these sources. (Abridged)