Black Hole-Neutron Star Binaries near Neutron Star Disruption Limit in the Mass Regime of Event GW230529

Understand

In May 2023, the LIGO Livingston observatory detected the likely black hole-neutron star (BHNS) merger GW230529_181500.

• That event is expected to be the merger of a 2.5-4.5 $M_{\odot}$ primary with a secondary compact object of mass between 1.2-2.0 $M_{\odot}$.
• This makes it the first BHNS merger with a significant potential for the production of electromagnetic (EM) counterparts, and provides further evidence for compact objects existing within the suspected lower mass gap.
• To produce post-merger EM transients, the component of the black hole spin aligned with the orbital angular momentum must be sufficiently high, allowing the neutron star to be tidally disrupted.