Accretion disk around a Schwarzschild black hole in asymptotic safety

TL;DR

This paper investigates how quantum gravity effects, modeled via asymptotic safety, influence the thermal and radiative properties of accretion disks around Schwarzschild black holes, with potential observational implications.

Contribution

It introduces a model of quantum gravity effects on accretion disks using a renormalization group improved Schwarzschild black hole, revealing modifications to disk properties and efficiency.

Findings

Increased maximum energy flux and luminosity due to quantum effects

Shift of the innermost stable circular orbit inward

Potential to detect quantum gravity signatures through astrophysical observations

Abstract

We study quantum gravity effects on radiation properties of thin accretion disks around a renormalization group improved (RGI-) Schwarzschild black hole. In the infrared (IR) limit of the asymptotically safe theory with higher derivatives, the running Newton coupling G(r) depends on a free parameter which encodes the quantum effects on the spacetime geometry. By varying this parameter, modifications to thermal properties of the disk as the time averaged energy flux, the disk temperature, the differential luminosity, and the conversion efficiency of accreting mass into radiation, are obtained. In addition to a shifting of the radius of the innermost stable circular orbit (ISCO) toward small values, we find an increase of the maximum values of these thermal properties and a greater efficiency than in the classical relativistic regime. We discuss astrophysical applications of these results by using observational data of the stellar-mass black hole candidate LMC X-3. Our findings could, in principle, be used to identify quantum gravity effects through astrophysical observations.