Universality of high-energy absorption cross sections for black holes

Abstract

We consider the absorption problem for a massless scalar field propagating in static and spherically symmetric black holes of arbitrary dimension endowed with a photon sphere. For this wide class of black holes, we show that the fluctuations of the high-energy absorption cross section are totally and very simply described from the properties (dispersion relation and damping) of the waves trapped near the photon sphere and therefore, in the eikonal regime, from the characteristics (orbital period and Lyapunov exponent) of the null unstable geodesics lying on the photon sphere. This is achieved by using Regge pole techniques. They permit us to make an elegant and powerful resummation of the absorption cross section and to extract then all the physical information encoded in the sum over the partial wave contributions. Our analysis induces moreover some consequences concerning Hawking radiation which we briefly report.Comment: v2: minor corrections reflecting the version to appear in PR

Quasinormal frequencies of black hole in the braneworld

“…So far, absorption and scattering properties of waves by various static spherically symmetric [54][55][56][57][58][59] and axially symmetric black holes [60] were studied. Here we extend these studies for the analysis of the absorption cross sections of massless scalar field by braneworld black holes.…”

Absorption and Scattering Cross Section of Regular Black Holes

“…We can also see that the total absorption cross section abs oscillates around the limit of geometrical optics. At the region ∼ 0.2, the total absorption sections create a regular oscillation pattern, and when ≫ 1, the absorption cross section tends to the geometric-optical limit of ℎ abs = 2 , where = /√ ( ), and the assumptions on imply the existence of a photon sphere located at which is the radius of unstable circular null geodesics [27]. …”

“…Décanini et al [14] show that the fluctuations of the highenergy absorption cross section are totally and very simply described from the properties of the waves trapped near the photon sphere. Batic et al [15] show that the case of orbiting scattering of massless spin 0, 1, and 2 particles from Schwarzschild black holes can be characterized by a sudden rise in | | at a critical angular momentum.…”

Scalar waves in regular Bardeen black holes: Scattering, absorption and quasinormal modes

“…15 which captures the important features of the absorption cross section, including the geodesic limit for higher frequencies. This approach is known as sinc approximation.…”