Neutron stars in Einstein-aether theory

TL;DR

This paper investigates how Einstein-aether theory, a modification of general relativity, affects the properties of non-rotating neutron stars, revealing lower maximum masses and larger surface redshifts within observationally consistent parameter ranges.

Contribution

It provides the first detailed analysis of neutron star properties in Einstein-aether theory, highlighting observable differences from general relativity.

Findings

Lower maximum neutron star masses within the theory's parameter range.

Larger surface redshifts at fixed mass compared to GR.

Minimal changes to the innermost stable circular orbit for black holes and neutron stars.

Abstract

As current and future experiments probe strong gravitational regimes around neutron stars and black holes, it is desirable to have theoretically sound alternatives to general relativity against which to test observations. Here we study the consequences of one such generalization, Einstein-aether theory, for the properties of non-rotating neutron stars. This theory has a parameter range that satisfies all current weak-field tests. We find that within this range it leads to lower maximum neutron star masses, as well as larger surface redshifts at a particular mass, for a given nuclear equation of state. For non-rotating black holes and neutron stars, the innermost stable circular orbit is only slightly modified in this theory.