Binary white dwarfs and decihertz gravitational wave observations: From the Hubble constant to supernova astrophysics

TL;DR

This paper investigates how decihertz gravitational wave detectors can measure distances to binary white dwarfs, enabling improved cosmological measurements and insights into supernova progenitors through multimessenger observations.

Contribution

It demonstrates the potential of decihertz gravitational wave interferometers to accurately measure distances and constrain cosmological parameters via multimessenger detections of white dwarf mergers.

Findings

Decihertz detectors can measure luminosity distances with better than 1% accuracy at 100 Mpc.

Multimessenger observations can tightly constrain the Hubble constant.

Results can improve understanding of supernova progenitors and cosmology.

Abstract

Coalescences of binary white dwarfs represent a copious source of information for gravitational wave interferometers operating in the decihertz band. Moreover, according to the double degenerate scenario, they have been suggested to be possible progenitors of supernovae (SNe) Type Ia events. In this paper we discuss the detectability of gravitational waves emitted by the inspiral of double white dwarfs. We focus on the constraints that can be derived on the source's luminosity distance, and on other binary's parameters, such as the angular momentum orientation. We explore the possibility of coincident detections of gravitational and electromagnetic signals; the latter comes from the observation of the supernova counterpart. Confirmation of the double degenerate scenario would allow one to use distances inferred in the gravitational wave channel to consistently calibrate SNe as standard candles. We find that decihertz gravitational wave interferometers can measure the luminosity distance with relative accuracy better than $1\%$ for binaries at 100 Mpc. We show how multimessenger observations can put strong constraints on the Hubble constant, which are tighter than current bounds at low redshift, and how they can potentially shed new light on the differences with early-universe measurements.