Contributed Talk - Splinter eROSITA

Tuesday, 13 September 2022, 15:20   (SFG 0140 / virtual eROSITA)

The stellar content of the first eROSITA all-sky survey

S. Freund1, S. Czesla2, P. Predehl1, J. Robrade2, P.C. Schneider2, J.H.M.M. Schmitt2
1 Max-Planck-Institut für extraterrestrische Physik, Gießenbachstraße 1, 85748 Garching, Germany 2 Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany

Nearly all types of stars are known to emit X-rays. For late-type stars with an outer convection zone, this X-ray emission is thought to be produced in a magnetically heated corona. Even for stars of the same spectral type, the X-ray emission can vary by orders of magnitude. The eROSITA all-sky survey (eRASS) will provide a sample of stellar X-ray sources of unprecedented size and quality. The data of the first all-sky survey (eRASS1) in the western hemisphere will be released to the public in less than one year. We present a complete Bayesian identification of the stellar content of eRASS1 applying a crossmatch with eligible Gaia DR3 counterparts. The procedure considers the geometric properties of the match and further properties as distance, color, and X-ray to bolometric flux ratio, and provides a stellar probability for all eRASS1 sources. The completeness and reliability of the identifications can be directly estimated from the stellar probabilities. Our unbiased and flux-limited identification allows us to study the dependence of the X-ray luminosity on properties like mass, luminosity class, and age.