Testing the Anomalous Growth of the Black Hole Radius from AGN

Andrea Addazi,Chenyang Qian,Antonino Marciano

doi:10.3390/galaxies6040107

Abstract

We analyze constraints on the anomalous growth of the black hole radius or the black hole spin from the X-rays spectrum data of Active Galactic Nuclei (AGN) in NGC 5506. The anomalous growth of the mass or of the spin of a black hole may be unveiled within the framework of models of alternative gravity, including f ( R ) -gravity. Our phenomenological analysis is based on an effective parametrization for the black hole Kerr metric, which is inspired by the antievaporating solutions discovered by Nojiri and Odintsov. We find tight constraints on the parameter space of anomalous metrics. Intriguingly, we find that a more than secularly growing solution can better fit current data. Our result opens a pathway towards a new phenomenological approach for testing predictions of general relativity and alternative theories of gravity.

Highlights

There exist several open problems of General Relativity (GR) both in the IR and in the UV regimes that may motivate its extension
Many puzzles still remain in our comprehension of the universe, including the nature of dark energy and dark matter, and the understanding of the homogeneity of the Cosmic Microwave Background (CMB) from a microphysical point of view, consistent with data we have on particle physics
Our effective time dependent parametrization of the anomalous Kerr metrics is inspired by the antievaporating solutions that can be recovered within the framework of extended theories of gravity—in particular f ( R)-gravity

Summary

Introduction

There exist several open problems of General Relativity (GR) both in the IR and in the UV regimes that may motivate its extension. We wish to emphasize that the antievaporation phenomena are not just a mean to recast idealistically unphysical models They are compatible with realistic extensions of GR that have passed the test-bed of cosmological and astrophysical limits. We cannot claim that we are able to discriminate whether: (i) a solution reflects the variation in time of the local matter flux inside the BH, in the AGN environment; (ii) this solution is a genuine hint in favor of exotic new BHs, beyond GR. These considerations highly motivate further analyses on other AGNs in the future

Anomalous Kerr Metric

Best Fit of the Spin Evolution in Time

Mass Fit

Conclusions and Remarks