Self-force as a probe of pressure anisotropies inside relativistic stars

Abstract

Scalar and electromagnetic fields in the exterior of a star contain information about the star's internal structure due to boundary conditions at its radius. Thus, measuring the self-force on the charge associated with the field can be used to probe information about a star's interior such as the strength of the pressure anisotropy of the fluid. Using the equations of state by Raposo et al. [Phys. Rev. D 99, 104072 (2019)], we found that for highly anisotropic stars of the same compactness, the self-force is higher for the more anisotropic star when we consider low compactnesses, which can make self-force a useful probe for anisotropy.