Speaker: Artur Avakyan, Aafia Zainab, Marvin Neumann, Victor Doroshenko, Joern Wilms (Eberhard Karls University of Tübingen, Otto-Friedrich-University Bamberg)

Title: Two new catalogs of XRBs and XMM follow-up of two XRB candidates discovered by eROSITA

Abstract: In order to better understand the population of known X-ray binaries (XRBs), as well as to reveal and identify potential XRB candidates, we have compiled two new up-to-date catalogs of low-mass (LMXBs) and high-mass (HMXBs) X-ray binaries. The catalogs contain names, coordinates, X-ray fluxes, as well as optical magnitudes and other characteristic properties of 349 LMXBs and 173 HMXBs, with the number of sources exceeding similar catalogs of previous years by more than 50%. Along with the catalogs, we report on XMM-Newton follow-up observations of two XRB candidates found in the first eROSITA survey. Based on the obtained results, in particular, observed X-ray spectra (XMM and eROSITA) and lack of pulsations, as well as properties of the unambiguously identified optical counterparts, we conclude that both candidates are more likely X-ray bright chromospherically active stars rather than XRBs, although in the case of eRASSU J161201-464623, the possibility that the source may be an early-type O-B star cannot be completely ruled out either. Considering that two other eROSITA XRB candidates selected for follow-up were eventually classified as XRBs, the overall accuracy of current selection is of the order of 50%, certainly leaving room for improvement. On the other hand, eROSITA survey data still hides a lot of similar sources, so the detailed analysis of such boundary cases is an important step towards identification of faint XRBs.