Chance coincidences between black hole low-mass X-ray binaries and supernova remnants

TL;DR

This paper argues that black hole low-mass X-ray binaries are unlikely to be physically associated with supernova remnants due to differing timescales, and most apparent associations are chance projections rather than true physical links.

Contribution

It provides a statistical analysis showing the low probability of physical association and refutes a specific proposed link between Swift J1728.9-3613 and SNR G351.9-0.9.

Findings

Less than 0.2% chance of physical association between BH LMXBs and SNRs.

Approximately 2 BH LMXBs are projected within SNRs from our perspective.

The proposed association between Swift J1728.9-3613 and G351.9-0.9 is likely a chance coincidence.

Abstract

I argue that black hole low-mass X-ray binaries (BH LMXBs) are very unlikely to be physically associated with supernova remnants (SNRs). The timescales of BH LMXBs are so much longer than those of SNRs, that there is only a 0.2% chance of any BH LMXB being identified within its natal SNR. However, the probability of a BH LMXB being projected within a SNR is significant; I estimate that 2 BH LMXBs should be projected within SNRs from our perspective. I look more closely at the suggestion by Balakrishnan and collaborators of an association between the BH X-ray binary Swift J1728.9-3613 and the SNR G351.9-0.9, and show that this is most likely a chance coincidence.