Rapidly Rotating Neutron Stars in Dilatonic Einstein-Gauss-Bonnet Theory

TL;DR

This paper constructs and analyzes rapidly rotating neutron stars within dilatonic Einstein-Gauss-Bonnet theory, revealing how the Gauss-Bonnet term influences their physical properties and stability limits compared to Einstein gravity.

Contribution

It provides the first detailed study of rapidly rotating neutron stars in dilatonic Einstein-Gauss-Bonnet theory, including their domain, physical properties, and universal relations.

Findings

Gauss-Bonnet term reduces maximum mass and central density of neutron stars.

Quadrupole moment decreases for rapid rotation but increases for slow rotation due to Gauss-Bonnet.

Universal quadrupole-moment and moment of inertia relation extends to this theory.

Abstract

We construct sequences of rapidly rotating neutron stars in dilatonic Einstein-Gauss-Bonnet theory, employing two equations of state for the nuclear matter. We analyze the dependence of the physical properties of these neutron stars on the Gauss-Bonnet coupling strength. For a given equation of state we determine the physically relevant domain of rapidly rotating neutron stars, which is delimited by the set of neutron stars rotating at the Kepler limit, the set of neutron stars along the secular instability line, and the set of static neutron stars. As compared to Einstein gravity, the presence of the Gauss-Bonnet term decreases this domain, leading to lower values for the maximum mass as well as to smaller central densities. The quadrupole moment is decreased by the Gauss-Bonnet term for rapidly rotating neutron stars, while it is increased for slowly rotating neutron stars. The universal relation between the quadrupole moment and the moment of inertia found in General Relativity appears to extend to dilatonic Einstein-Gauss-Bonnet theory with very little dependence on the coupling strength of the Gauss-Bonnet term. The neutron stars carry a small dilaton charge.