SRG/eROSITA Survey in the Lockman Hole: Classification of X-ray Sources
Abstract
We have classified the X-ray sources detected by the SRG/eROSITA telescope in the deep Lockman Hole survey. The goal of the classification has been the separation of the sources into Galactic and extragalactic objects. For this purpose, we have used the results of our previous cross-match of X-ray sources with optical catalogs. For the classification we have used the flux ratio $F_{\textrm{x}}/F_{\textrm{o}}$ and information about the source optical extent. As a result, of the 6885 X-ray sources in the eROSITA catalog, 357, 5929, and 539 have been classified as, respectively, Galactic, extragalactic, and hostless, i.e., having no optical counterparts in the optical catalogs under consideration, while 60 have remained unclassified due to the insufficient reliability of optical photometry. We have estimated the selection precision and recall for the extragalactic (99.9 and 98.9${%}$, respectively) and Galactic (91.6 and 99.7${%}$) sources. Based on our classification, we have constructed the curves of cumulative number counts for the Galactic and extragalactic sources in the Lockman Hole field.
- Publication:
-
Astronomy Letters
- Pub Date:
- December 2022
- DOI:
- 10.1134/S1063773722110020
- arXiv:
- arXiv:2307.14737
- Bibcode:
- 2022AstL...48..755B
- Keywords:
-
- X-ray sky surveys;
- Lockman Hole;
- active galactic nuclei;
- quasars;
- X-ray active stars;
- source counts;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Published in Astronomy Letters