Compact stellar remnants like white dwarfs, neutron stars and black holes are important probes of matter under extreme conditions of gravity, density, temperature and magnetic fields. A large fraction of these stellar remnants reside in binary systems providing insights into massive star evolution, accretion and some outstanding questions in astrophysics like progenitors of SN 1a and...
Despite the potential of GAIA DR3 to reveal a large population of black holes (BHs), only a few BHs have been discovered to date in orbit with luminous stars without an X-ray counterpart. It has recently been shown that black holes in orbit with main sequence companions seldom form accretion disks, from where observable X-ray flux is conventionally thought to be produced. Yet, even without...
Ultraluminous X-ray sources (ULX) are thought to be dominated by the most luminous X-ray binaries, many of which accrete at super-Eddington rates, although some small fraction of the population may harbor intermediate-mass black holes. We present a catalog of ULX candidates identified in the first eROSITA all-sky survey (eRASS1) consisting of 89 strong ULX candidates which we use for further...
The eROSITA all-sky X-ray (0.2-8.0 keV) survey, provides the first unbiased census of the X-ray emission of galaxies, allowing us to study the emission from X-ray binaries (XRBs) and the hot interstellar medium in the full range of stellar population parameters present in the local Universe. By combining the updated version of the HECATE v2.0 value-added catalogue of nearby galaxies...
X-ray binaries (XRBs) are our most accessible way to probe populations of Galactic compact objects in the X-ray regime, and offer crucial constraints on Galactic stellar evolution models. Previously reported distributions of XRBs plateau at intermediate luminosities of $10^{35}$ erg/s, and only reach fluxes down to a few $10^{-12}$ cgs. eROSITA’s improved sensitivity allows us to extend this...
Nova explosions are thermonuclear events on top of an accreting white dwarf in a cataclysmic variable (CV) or a symbiotic system. The nova event results in the increase of the optical luminosity by 7-8 orders of magnitude. That makes the nova outburst detectable at any distance in the Galaxy, in the Local Group and even beyond the Local Group. However, due to the resulting distance...
