Analysis of the subsolar-mass black hole candidate SSM200308 from the second part of the third observing run of Advanced LIGO-Virgo

Understand

A follow-up of a subsolar black hole candidate identified in the second part of the third observing run of the LIGO-Virgo-KAGRA collaboration is carried out.

• With a search signal-to-noise ratio of $8.90$ and a false-alarm rate of 1 per 5 years, close to the usual thresholds for claiming a gravitational-wave event, we cannot exclude a noise origin.
• A complete Bayesian parameter estimation of this candidate, denoted SSM200308, reveals that if the signal originates from a compact binary coalescence, the component masses are $m_1= 0.62^{+0.46}_{-0.20} M_{\odot}$ and $m_2 = 0.27^{+0.12}_{-0.10} M_{\odot}$ (90% credible intervals) with at least one component being firmly subsolar, below the minimum mass of a neutron star.
• This discards the hypothesis that the signal comes from a standard binary neutron star.