# Spatial dispersion of light rays propagating through a plasma in Kerr spacetime

## TL;DR

This paper studies how light disperses when traveling through plasma around a Kerr black hole, revealing frequency-dependent effects that impact pulsar signal detection near the Galactic center.

## Contribution

It introduces a Hamiltonian approach to analyze light propagation in plasma on Kerr spacetime, highlighting the combined gravitational and plasma dispersion effects.

## Key findings

- Dispersion varies with ray frequency and impact parameter.
- Gravitational and plasma effects cause measurable space and time dispersion.
- Implications for detecting pulsar signals near the Galactic center.

## Abstract

We investigate the propagation of light through a plasma on a background Kerr spacetime via a Hamiltonian formulation. The behaviour of light when propagating through a vacuum and through a plasma is not the same; the convolution of gravitational and plasma effects gives rise to a dispersion in both space and time. The magnitude of the dispersion is a strong function of both the ray frequency and impact parameter. We discuss implications for the detection of gravitationally bent pulsar beams near the Galactic centre.