Accurate precision Cosmology with redshift unknown gravitational wave sources

TL;DR

This paper introduces a method to determine the universe's expansion history using gravitational wave sources with unknown redshifts by leveraging their clustering with galaxies of known redshift, applicable across various detectors and other astrophysical sources.

Contribution

It presents a novel technique to infer redshifts of gravitational wave sources through clustering, enabling precise cosmological measurements without direct redshift information.

Findings

Enables measurement of the Hubble constant using unknown redshift gravitational waves.

Applicable to high redshift sources detectable by future space-based detectors.

Extends to other astrophysical transients like supernovae and fast radio bursts.

Abstract

Gravitational waves can provide an accurate measurement of the luminosity distance to the source, but cannot provide the source redshift unless the degeneracy between mass and redshift can be broken. This makes it essential to infer the redshift of the source independently to measure the expansion history of the Universe. We show that by exploiting the clustering scale of the gravitational wave sources with galaxies of known redshift, we can infer the expansion history from redshift unknown gravitational wave sources. By using gravitational wave sources of unknown redshift that are detectable from the network of gravitational wave detectors with Advanced LIGO design sensitivity, we will be able to obtain accurate and precise measurements of the local Hubble constant, the expansion history of the universe, and the gravitational wave bias parameter, which captures the distribution of gravitational wave sources with respect to the redshift tracer distribution. While we showcase its application to low redshift gravitational waves, this technique will be applicable also to the high redshift gravitational wave sources detectable from Laser Interferometer Space Antenna (LISA), Cosmic Explorer (CE), and Einstein Telescope (ET). Moreover, this method will also be applicable to samples of supernovae and fast radio bursts with unknown or photometric redshifts.