arXiv subjects

Fabián H. Zuluaga

Publications and source records attributed to Fabián H. Zuluaga.

2 recordsLinked to original sources

arXiv2021

Accretion disk around a Schwarzschild black hole in asymptotic safety

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.

gr-qc↗

arXiv2021

Black holes in asymptotic safety with higher derivatives: accretion and stability analysis

We review the issue of steady spherically symmetric accretion onto a renormalization group improved Schwarzschild space-time which is solution to an asymptotically safe theory (AS) containing high-derivative terms. We use a Hamiltonian dynamical system approach for the analysis of the accretion of four types of isothermal test fluids: ultra-stiff fluid, ultra-relativistic fluid, radiation fluid, and sub-relativistic fluid. An important outcome of our study is that, contrary to what claimed in a recent work, there exist physical solutions for the accretion of an ultra-relativistic fluid in AS which include subsonic, supersonic and transonic regimes. We also study quantum corrections to the known stability of the accretion in general relativity (GR). To this end we use a perturbative procedure based on the continuity equation with the mass accretion rate being the perturbed quantity. Two classes of perturbations are studied: standing waves and travelling waves. We find that quantum gravity effects either enhance or diminish the stability of the accretion depending on the type of test fluid and depending on the radial distance to the central object.

gr-qc↗