Effects of a Late Gravitational Transition on Gravitational Waves and Anticipated Constraints

TL;DR

This paper explores how a sudden change in the universe's expansion rate, possibly caused by a shift in the gravitational constant, affects gravitational waves and how future experiments can constrain such transitions.

Contribution

It models the evolution of gravitational waves across a cosmological singularity and assesses how future gravitational wave data can improve constraints on these phenomena.

Findings

Future gravitational wave data can reduce uncertainties in transition parameters by up to three times.

The evolution of gravitational waves can be modeled through a sudden cosmological singularity.

Current data already place some constraints on the magnitude of gravitational transitions.

Abstract

We investigate the evolution of gravitational waves through discontinuous evolution (transition) of the Hubble expansion rate $H(z)$ at a sudden cosmological singularity, which may be due to a transition of the value of the gravitational constant. We find the evolution of the scale factor and the gravitational wave waveform through the singularity by imposing the proper boundary conditions. We also use existing cosmological data and mock data of future gravitational wave experiments (the ET) to impose current and anticipated constraints on the magnitude of such a transition. We show that mock data of the Einstein Telescope can reduce the uncertainties by up to a factor of three depending on the cosmological parameter considered.