Phenomenological aspects of black holes beyond general relativity

While singularities are inevitable in the classical theory of general relativity, it is commonly believed that they will not be present when quantum gravity effects are taken into account in a consistent framework. In particular, the structure of black holes should be modified in frameworks beyond general relativity that aim at regularizing singularities. Being agnostic on the nature of such theory, in this paper we classify the possible alternatives to classical black holes and provide a minimal set of phenomenological parameters that describe their characteristic features. The introduction of these parameters allows us to study, in a largely model-independent manner and taking into account all the relevant physics, the phenomenology associated with these quantum-modified black holes. We perform an extensive analysis of different observational channels and obtain the most accurate characterization of the viable constraints that can be placed using current data. Aside from facilitating a critical revision of previous work, this analysis also allows us to highlight how different channels are capable of probing certain features but are oblivious to others, and pinpoint the theoretical aspects that should be addressed in order to strengthen these tests.

Figure 1

Only a fraction $\mathrm{\Delta }\mathrm{\Omega }/2\pi$ of geodesics emitted isotropically at a point on the surface $r=R$ can escape for ultracompact configurations.

Figure 2

On the left: Initial state in which matter starts falling at a rate $\dot{M}$ from the accretion disk onto the CMO. On the right: steady state in which the energy emitted from the CMO and reaching the accretion disk is $\dot{E}=\dot{M}$.

Figure 3

Representation of Eq. (35) for $\mathrm{\Delta }=0.1$ (light gray), $\mathrm{\Delta }=0.01$ (gray), and $\mathrm{\Delta }=0.001$ (dark gray).

Figure 4

Exponential peeling of outgoing geodesics reflected at $r=R$. Even if the ingoing distribution of energy has low density (light gray region), the accumulation of geodesics around the gravitational radius produces high densities (dark gray region) that result in large backreaction effects on the background geometry.