Light Deflection in Plasma in the Hartle-Thorne Metric and in Other Axisymmetric Spacetimes with a Quadrupole Moment

TL;DR

This paper investigates how plasma affects light deflection around rotating and static gravitating objects with quadrupole moments, comparing the Hartle-Thorne and Kerr metrics, and providing analytic and graphical results.

Contribution

It provides a general analytic expression for light deflection in plasma around axisymmetric spacetimes with quadrupole moments, focusing on the Hartle-Thorne and Kerr metrics.

Findings

Quadrupole moments significantly influence light trajectories.

Analytic formulas for deflection angles are derived in weak field limits.

Graphical comparisons illustrate the effects of different metrics on light bending.

Abstract

The light propagation in plasma medium around stationary gravitating objects is studied in the geometrical optics limit. Static metrics with quadrupole moments are considered, however, the main attention is paid to the stationary Hartle-Thorne metric and Kerr metric. Their different effects on the light deflection are compared. The deflection angle is given in a general analytic form, the detailed calculations are performed in the weak field limits and illustrated graphically. The trajectories of the light rays are constructed and compared, emphasizing the role of the quadrupole moment.