The Reliability of the Low-latency Estimation of Binary Neutron Star Chirp Mass

Abstract

Abstract The LIGO and Virgo Collaborations currently conduct searches for gravitational waves from compact binary coalescences in real time. For promising candidate events, a sky map and distance estimation are released in low latency to facilitate their electromagnetic follow-up. Currently, no information is released about the masses of the compact objects. Recently, Margalit & Metzger suggested that knowledge of the chirp mass of the detected binary neutron stars could be useful to prioritize the electromagnetic follow-up effort, and urged the LIGO-Virgo collaboration to release chirp mass information in low latency. One might worry that low-latency searches for compact binaries make simplifying assumptions that could introduce biases in the mass parameters: neutron stars are treated as point particles with dimensionless spins below 0.05 perfectly aligned with the orbital angular momentum. Furthermore, the template bank used to search for them has a finite resolution. In this paper we show that none of these limitations can introduce chirp mass biases larger than ∼10−3 M ⊙. Even the total mass is usually accurately estimated, with biases smaller than 6%. The mass ratio and effective inspiral spins, on the other hand, can suffer from more severe biases.