Circular geodesics in a New Generalization of q-metric

TL;DR

This paper explores how external quadrupole fields influence circular geodesics and the ISCO in a new generalization of the q-metric, providing insights into the spacetime structure around deformed compact objects.

Contribution

It introduces a novel generalization of the q-metric incorporating external quadrupole fields and analyzes their effects on circular geodesics and ISCO locations.

Findings

External quadrupole fields significantly alter geodesic stability.

The interplay of intrinsic and external quadrupoles shifts the ISCO.

New metric generalization captures more realistic astrophysical scenarios.

Abstract

This paper introduces an alternative generalization of the static solution with quadrupole moment, the $\rm q$-metric, that describes a deformed compact object in the presence of the external fields characterized by multipole moments. In addition, we also examine the impact of the external fields up to quadrupole on the circular geodesics and the interplay of these two quadrupoles on the place of the innermost stable circular orbit (ISCO) in the equatorial plane.