Detecting Baryon Acoustic Oscillations with third generation gravitational wave observatories

TL;DR

This paper investigates the potential of third-generation gravitational wave detectors to independently detect Baryon Acoustic Oscillations through binary neutron star mergers, offering a new cosmological probe.

Contribution

It demonstrates that 3G GW observatories can precisely measure BAO features from GW data alone, which was not possible with current detectors.

Findings

3G detectors can localize ~1000 mergers per year within 1 square degree.

BAO features can be detected at different redshifts with high confidence.

The study provides evidence ratios favoring BAO detection at specific redshifts.

Abstract

We explore the possibility of detecting Baryon Acoustic Oscillations (BAO) solely from gravitational wave observations of binary neutron star mergers with third generation (3G) gravitational wave (GW) detectors like Cosmic Explorer and the Einstein Telescope. These measurements would provide a new independent probe of cosmology. The detection of the BAO peak with current generation GW detectors (solely from GW observations) is not possible because i) unlike galaxies, the GW mergers are poorly localized and ii) there are not enough merger events to probe the BAO length scale. With the 3G GW detector network, it is possible to observe $\sim \mathcal{O}(1000)$ binary neutron star mergers per year localized well within one square degree in the sky for redshift $z \leq 0.3$. We show that 3G observatories will enable precision measurements of the BAO feature in the large-scale two-point correlation function; the effect of BAO can be independently detected at different reshifts, with a log-evidence ratio of $\sim$ 23, 17, or 3 favouring a model with a BAO peak at redshift of 0.2, 0.25, or 0.3, respectively, using a redshift bin corresponding to a shell of thickness $150 h^{-1}$ Mpc.