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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.