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Session: Extragalactic Astronomy and Astrophysics

Name: Mr. Elias Kyritsis (IA-FORTH & Univ. of Crete)
Coauthors: Zezas Andreas (Institute of Astrophysics -FORTH/ Physics Department - UoC)
Haberl Frank (Max-Planck-Institut fuer Extraterrestrische Physik (MPE))
Wilms Joern (Dr Karl Remeis Observatory)
Sasaki Manami (Dr Karl Remeis Observatory)
Basu-Zych Antara (University of Maryland)
Vulic Neven (Goddard Space Flight Center (GSFC/NASA))
Hornschemeier Ann (Goddard Space Flight Center (GSFC/NASA))
Weber Phillipp (Dr Karl Remeis Observatory)
Type: Oral
Title: The first unbiased survey of star-forming galaxies with eROSITA: Scaling relations and a population of X-ray luminous starbursts
Abstract:

eROSITA, the first 0.2-8.0 keV all-sky X-ray survey, provides the first unbiased census of X-ray galaxies in the local Universe. We combine the first scan of eROSITA (eRASS:1) with the HECATE catalog of nearby galaxies (D ≤ 200Mpc) resulting in a sample of ∼20000 highly-secure star-forming galaxies. This allows us to investigate the Lx-SFR-M∗-Metallicity relation with less biased and larger sample than any other previous study. Our analysis reveals a population of star-forming galaxies with (Lx ≥ 1040 erg/s) and significant deviations from the standard scaling relations. By stacking the X-ray emission of the galaxies in (SFR,M∗,D) bins we find that: i) the average scaling relations resulting from this unbiased sample are still significantly higher than those currently used, ii) there is a strong anti-correlation between metallicity, age and X-ray luminosity. Based on these results we provide new calibration of the scaling relations, we quantify the scatter, and we investigate the nature of the most X-ray luminous galaxies which tend to be young low-metallicity starburst galaxies serving as analogs for high-z galaxies.