Parameter estimation for binary black holes with networks of third generation gravitational-wave detectors

TL;DR

This paper evaluates how third-generation gravitational-wave detectors will improve parameter estimation of binary black holes across various masses and redshifts, highlighting the benefits of multiple detectors for localization and mass measurement.

Contribution

It provides a quantitative analysis of the expected parameter estimation accuracy for future third-generation GW detectors with different network configurations.

Findings

Two detectors yield poor mass estimates.

Adding more detectors improves sky localization.

Spin measurements are less affected by detector network size.

Abstract

The two binary black-hole (BBH) coalescences detected by LIGO, GW150914 and GW151226, were relatively nearby sources, with a redshift of ~0.1. As the sensitivity of Advanced LIGO and Virgo increases in the next few years, they will eventually detect stellar-mass BBHs up to redshifts of ~1. However, these are still relatively small distances compared with the size of the Universe, or with those encountered in most areas of astrophysics. In order to study BBH during the epoch of reionization, or black holes born from population III stars, more sensitive instruments are needed. Third-generation gravitational-wave detectors, such as the Einstein Telescope or the Cosmic Explorer are already in an advanced R&D stage. These detectors will be roughly a factor of 10 more sensitive in strain than the current generation, and be able to detect BBH mergers beyond a redshift of 20. In this paper we quantify the precision with which these new facilities will be able to estimate the parameters of stellar-mass, heavy, and intermediate-mass BBH as a function of their redshifts and the number of detectors. We show that having only two detectors would result in relatively poor estimates of black hole intrinsic masses; a situation improved with three or four instruments. Larger improvements are visible for the sky localization, although it is not yet clear whether BBHs are luminous in the electromagnetic or neutrino band. The measurement of the spin parameters, on the other hand, do not improve significantly as more detectors are added to the network since redshift information are not required to measure spin.