# The reliability of the low-latency estimation of binary neutron star chirp mass

## TL;DR

This paper evaluates the accuracy of low-latency binary neutron star chirp mass estimation in gravitational wave detection, showing biases are minimal and supporting real-time mass information release for electromagnetic follow-up.

## Contribution

It demonstrates that low-latency searches produce reliable chirp mass estimates with negligible bias, enabling prompt electromagnetic follow-up efforts.

## Key findings

- Chirp mass biases are smaller than 10^{-3} solar masses.
- Total mass estimates are accurate with biases under 6%.
- Mass ratio and spin estimates can have larger biases.

## 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 and Metzger (2019) have suggested that knowledge of the chirp mass of the detected binary neutron stars could be useful to prioritize the electromagnetic follow-up effort, and have 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 $0.05$ and 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 $\sim 10^{-3}~M_\odot$. 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.