Stellar structure in $f(R,T)$ gravity: some exact solutions

TL;DR

This paper derives exact solutions for stellar structures within $f(R,T)$ gravity, revealing how modifications to gravity can alter star compactness limits and potentially inform astrophysical constraints.

Contribution

It provides new exact solutions for stellar models in $f(R,T)$ gravity with specific equations of state, highlighting the impact on star compactness limits.

Findings

Quark matter stars can have increased compactness limits.

Solutions correspond to specific $ extit{lambda}$ values affecting star properties.

Modified Buchdahl limit approaches black hole compactness for positive $ extit{lambda}$.

Abstract

We find some exact solutions for constant-density and quark matter equations of state in stellar structure models framed within the $f(R,T)=R+\lambda \kappa^2 T$ theory of gravity, where $R$ is the curvature scalar, $T$ the trace of the stress-energy tensor, and $\lambda$ some constant. These solutions correspond to specific values of the constant $\lambda$, and represent different compactness states of the corresponding stars, though only those made of quark matter can be regarded as physical. The latter modify the compactness (Buchdahl) limit of neutron stars upwards for $\lambda>0$ until saturating the one of black holes. Our results show that it is possible to find useful insights on stellar structure in this class of theories, a fact that could be used for obtaining constraints on limiting masses such as the minimum hydrogen burning mass.