Testing loop quantum gravity by quasi-periodic oscillations: rotating blackholes

TL;DR

This paper models rotating black holes influenced by loop quantum gravity effects and uses quasi-periodic oscillations from X-ray binaries to constrain the quantum parameter, revealing degeneracies in the model.

Contribution

It introduces a simplified rotating black hole model incorporating loop quantum gravity effects and constrains it using QPO data, highlighting parameter degeneracies.

Findings

Estimated quantum parameter λ with uncertainties for two geometries.

Constrained λ to approximately 0.15 and 0.11 at 1σ confidence levels.

Identified degeneracy in parameter space limiting precision of constraints.

Abstract

We investigate a compelling model of a rotating black hole that is deformed by the effects of loop quantum gravity (LQG). We present a simplified metric and explore two distinct geometries: one in which the masses of the black hole and white hole are equal, and another in which they differ. Our analysis yields the radius of the innermost stable circular orbits (ISCO), as well as the energy and angular momentum of a particle within this framework. Additionally, we find the frequency of the first-order resonance separately. We constrain the model by the quasi-periodic oscillations (QPO) of the X-ray binary GRO J1655-40. We show that $\lambda=0.15^{+0.23}_{-0.14}$ at $1\sigma$ confidence level for equal mass black hole and white hole geometry. For the other geometry we get $\lambda=0.11^{+0.07}_{-0.07}$ at $1\sigma$ confidence level.We encounter a degeneracy in the parameter space that hinders our ability to constrain $\lambda$ with greater precision.