A possible testbed for warped extra dimension from the angle of Buchdahl's limit

TL;DR

This paper explores how a five-dimensional warped spacetime with a scalar field affects stellar structures, revealing that the presence of a modulus field can alter Buchdahl's limit beyond general relativity predictions, offering a potential test for extra dimensions.

Contribution

It demonstrates that a bulk scalar field in a warped extra dimension can modify the Buchdahl's limit for stars, providing a new way to test higher-dimensional theories.

Findings

Buchdahl's limit can be exceeded due to the modulus field.

The scalar field stabilizes the extra dimension while influencing stellar properties.

Potential observational signatures for extra dimensions are identified.

Abstract

We consider a five dimensional AdS warped spacetime in presence of a massive scalar field in the bulk. The scalar field potential fulfills the requirement of modulus stabilization even when the effect of backreaction of the stabilizing field is taken into account. In such a scenario, we investigate the possible role of modulus field on a compact stellar structure from the perspective of four dimensional effective theory. Our result reveals that in the presence of the modulus field, the upper bound of mass-radius ratio (generally known as Buchdahl's limit) of a star can go beyond the general relativity prediction. Interestingly this provides a natural testbed for the existence of such higher dimensional modulus field.