Eccentric extreme mass-ratio inspirals: A gateway to probe quantum gravity effects

TL;DR

This paper explores how gravitational wave observations from eccentric extreme mass-ratio inspirals can potentially detect quantum gravity effects predicted by loop quantum gravity, offering a new way to test fundamental physics.

Contribution

It derives analytical orbital dynamics and gravitational waveforms for LQG-inspired black holes in EMRIs, and assesses LISA's ability to distinguish these from classical Kerr black holes.

Findings

LISA can detect LQG effects with a parameter as small as 2×10^{-6}

Orbital evolution and waveforms are analytically modeled for LQG black holes

Constraints on LQG parameters can reach a fractional error of 10^{-6}

Abstract

We examine a loop quantum gravity (LQG) inspired rotating black hole, treating it as a central supermassive black hole (SMBH) in an extreme mass-ratio inspiral (EMRI) system, where an inspiralling object exhibits eccentric motion around the SMBH. With the orbital dynamics, we derive analytical expressions for the rate of change of orbital energy and angular momentum, as well as orbital evolution, and subsequently generate the gravitational waveforms. To evaluate the difference between EMRI waveforms emitted from the Kerr black hole and a spinning black hole in LQG, we compute the dephasing and mismatch using the Laser Interferometer Space Antenna (LISA) observation. Our result indicates that LISA can distinguish the modified effect of LQG with a parameter as small as $2\times10^{-6}$. The constraint on a parameter in LQG using the Fisher information matrix can be obtained within a fraction error of $10^{-6}$.