Scattering of Scalar Waves by Schwarzschild Black Hole Immersed in Magnetic Field

TL;DR

This paper investigates how magnetic fields influence scalar wave scattering by Schwarzschild black holes, revealing oscillatory absorption cross sections and magnetic effects on scattering flux and glory phenomena.

Contribution

It introduces a quantum scattering analysis of scalar waves around black holes immersed in magnetic fields, highlighting new effects on absorption and scattering cross sections.

Findings

Absorption cross sections oscillate around the geometric optical value at high frequencies.

Magnetic fields weaken absorption cross sections at low frequencies.

Magnetic fields narrow the scattering flux and enhance the glory peak at certain frequencies.

Abstract

The magnetic field is one of the most important constituents of the cosmic space and one of the main sources of the dynamics of interacting matter in the universe. The astronomical observations imply the existence of a strong magnetic fields of up to $10^4-10^8G$ near supermassive black holes in the active galactic nuclei and even around stellar mass black holes. In this paper, with the quantum scattering theory, we analysis the Schr\"{o}edinger-type scalar wave equation of black hole immersed in magnetic field and numerically investigate its absorption cross section and scattering cross section. We find that the absorption cross sections oscillate about the geometric optical value in the high frequency regime. Furthermore in low frequency regime, the magnetic field makes the absorption cross section weaker and this effect is more obviously on lower frequency brand. On the other hand, for the effects of scattering cross sections for the black hole immersed in magnetic field, we find that the magnetic field makes the scattering flux weaker and its width narrower in the forward direction. We find that there also exists the glory phenomenon along the backforward direction. At fixed frequency, the glory peak is higher and the glory width becomes narrower due to the black hole immersed in magnetic field.