Gravitational waves from equatorially eccentric extreme mass ratio inspirals around swirling Kerr black holes

TL;DR

This study explores how a new swirling parameter in Kerr black holes influences gravitational waves from eccentric EMRIs, revealing phase shifts and effects on waveform confusion, with implications for gravitational wave astronomy.

Contribution

It introduces the swirling Kerr black hole solution and analyzes its impact on EMRI gravitational waveforms, highlighting differences from traditional spin effects.

Findings

Swirling parameter causes delayed phase shifts in waveforms.

Increased swirling enhances eccentricity variations, reduces semi-latus rectum variations.

Effects differ significantly from those of black hole spin parameter.

Abstract

The swirling-Kerr black hole is a novel solution of vacuum general relativity and has an extra swirling parameter characterizing the rotation of spacetime background. We have studied the gravitational waves generated by extreme mass ratio inspirals (EMRIs) along eccentric orbits on equatorial plane in this novel swirling spacetime. Our findings indicate that this swirling parameter leads to a delayed phase shift in the gravitational waveforms. Furthermore, we have investigated effects of the swirling parameter on the potential issue of waveform confusion caused by the orbital eccentricity and semi-latus rectum parameters. As the swirling parameter increases, the relative variations in the eccentricity increase, while the variations in the semi-latus rectum decrease rapidly. These trends of the changes related to the orbital eccentricity and the semi-latus rectum with the swirling parameter resemble those observed with the MOG parameter in the Scalar-Tensor-Vector-Gravity (STVG) theory, but with different rates of change. Furthermore, our results also reveal that effects of the background swirling parameter on the relative variations in the eccentricity and the semi-latus rectum are distinctly different from those of the black hole spin parameter. These results provide deeper insights into the properties of EMRI gravitational waves and the background's swirling.