Stellar binaries that survive supernovae

Abstract

Abstract The number of binaries containing black holes (BH) or neutron stars (NS) depends critically on the fraction of binaries that survive supernova (SN) explosions. We searched for surviving star plus remnant binaries in a sample of 49 supernova remnants (SNR) containing 23 previously identified compact remnants and three high-mass X-ray binaries (HMXB), finding no new interacting or non-interacting binaries. The upper limits on any main-sequence stellar companion are typically $\lesssim 0.2\, \mathrm{M}_\odot$ and are at worst $\lesssim 3\, \mathrm{M}_\odot$. This implies that f < 0.1 of core-collapse SNRs contain a non-interacting binary, and f = 0.083 (0.032 < f < 0.17) contain an interacting binary at 90 per cent confidence. We also find that the transverse velocities of HMXBs are low, with a median of only 12 km s−1 for field HMXBs, so surviving binaries will generally be found very close to the explosion centre. We compare the results to a ‘standard’ StarTrack binary population synthesis (BPS) model, finding reasonable agreement with the observations. In particular, the BPS models predict that 6 per cent of initial binaries leave a star plus remnant binary, or 5 per cent of SNRs assuming an 84 per cent binary fraction.