Circular time-like geodesics around a charged spherically symmetric dilaton black hole

TL;DR

This paper analyzes the existence and stability of circular time-like geodesics around a charged spherically symmetric dilaton black hole, determining key orbital radii and comparing results with previous studies.

Contribution

It provides a detailed analysis of stable and unstable circular orbits around a dilaton black hole using the exact Gibbons-Maeda-Garfinkle-Horowitz-Strominger solution, including new calculations of orbital radii.

Findings

Determined the radius of the innermost stable circular orbit.

Calculated the shortest circular orbit radius.

Compared orbital characteristics with previous models.

Abstract

In this note we examine the circular time-like geodesics near a spherically symmetric dilaton black hole, described using the exact solution for a static charged black hole found by Gibbons and Maeda and, independently, by Garfinkle, Horowitz and Strominger. The existence and stability of the circular orbits are analysed using the effective potential of a free material test particle moving on time-like geodesic near this black hole. We determine the radius of the innermost stable circular orbit, the radius of the shortest circular orbit and compare our results with those obtained by other authors for specific values of the parameters involved in our analysis.