Effect of a second compact object on stable circular orbits

TL;DR

This paper explores how the presence of a second compact object influences the stability of circular orbits around a primary object, revealing that the mass ratio and separation affect orbit stability boundaries.

Contribution

It introduces a detailed analysis of stable circular orbits in a dihole spacetime, identifying critical mass ratios and separation ranges affecting orbit stability.

Findings

Stable circular orbit regions depend on mass ratio and separation.

Four distinct mass ratio regimes determine orbit stability boundaries.

Three critical values mark transitions in orbit stability regions.

Abstract

We investigate how stable circular orbits around a main compact object appear depending on the presence of a second one by using the Majumudar--Papapetrou dihole spacetime, which consists of the two extremal Reissner--Nordstr\" om black holes with different masses. While the parameter range of the separation of the two objects is divided due to the appearance of stable circular orbits, this division depends on its mass ratio. We show that the mass ratio range separates into four parts, and we find three critical values as the boundaries.