The X-ray binaries in M83: Will any of them form gravitational wave sources for LIGO-VIRGO-KAGRA?

Abstract

There are 214 X-ray point sources (LX > 1035 erg s−1) identified as X-ray binaries (XRBs) in the nearby spiral galaxy M83. Since XRBs are powered by accretion onto a neutron star (NS) or a black hole (BH) from a companion or donor star, these systems are promising progenitors of merging double compact objects (DCOs): BH-BH, BH-NS, or NS-NS systems. The connection (i.e., XRBs evolving into DCOs) may provide some hints to the as-yet-unanswered question: what is the origin of the LIGO, Virgo, and KAGRA mergers? Available observations do not allow us to determine what the final fate of the XRBs observed in M83 will be. However, we can use an evolutionary model of isolated binaries to reproduce the population of XRBs in M83 by matching model XRB numbers, types, and luminosities to observations. Knowing the detailed properties of M83 model XRBs (donor and accretor masses, and their evolutionary ages and orbits), we follow their evolution to the deaths of donor stars to check whether any merging DCOs are formed. Although all merging DCOs in our isolated binary evolution model go through the XRB phase (defined as reaching X-ray luminosity from RLOF or wind accretion onto NSs or BHs above 1035 erg s−1), only very few XRBs evolve to form merging (in Hubble time) DCOs. For M83, with its solar-like metallicity stars and continuous star formation, we find that only ∼1 − 2% of model XRBs evolve into merging DCOs depending on the adopted evolutionary physics. This is caused by (i) the merger of the donor star with a compact object during the common envelope phase, (ii) a binary disruption at the supernova explosion of a donor star, (iii) the formation of a DCO on a wide orbit (merger time longer than Hubble time).