Testing Kerr Black Hole Mimickers with Quasi-Periodic Oscillations from GRO J1655-40

TL;DR

This study uses quasi-periodic oscillations to test whether the compact object in GRO J1655-40 is a Kerr black hole or a mimicker like a traversable wormhole or a regular black hole, finding data slightly favors a regular black hole with one horizon.

Contribution

It introduces a method to distinguish Kerr black holes from mimickers using QPOs within the relativistic precession model and applies it to GRO J1655-40 data.

Findings

Data is consistent with Kerr black hole but favors a regular black hole with one horizon.

The relativistic precession model effectively constrains the nature of compact objects.

Regular black hole models are compatible with observed QPO frequencies.

Abstract

The measurements of quasi-periodic oscillations (QPOs) provide a quite powerful tool to test the nature of astrophysical black hole candidates in the strong gravitational field regime. In this paper, we use QPOs within the relativistic precession model to test a recently proposed family of rotating black hole mimickers, which reduce to the Kerr metric in a limiting case, and can represent traversable wormholes or regular black holes with one or two horizons, depending on the values of the parameters. In particular, assuming that the compact object of GRO J1655-40 is described by a rotating black hole mimicker, we perform a $\chi$-square analysis to fit the parameters of the mimicker with two sets of observed QPO frequencies from GRO J1655-40. Our results indicate that although the metric around the compact object of GRO J1655-40 is consistent with the Kerr metric, a regular black hole with one horizon is favored by the observation data of GRO J1655-40.