Static and slowly rotating neutron stars in scalar-tensor theory with self-interacting massive scalar field

TL;DR

This paper investigates how self-interacting massive scalar fields in scalar-tensor theories affect static and slowly rotating neutron stars, showing that significant deviations from general relativity remain possible within observational constraints.

Contribution

It extends scalar-tensor theories by including self-interaction in the scalar field potential, analyzing its impact on neutron star properties and deviations from GR.

Findings

Self-interaction suppresses scalar fields in neutron stars.

Large deviations from GR are still possible with observationally consistent parameters.

Massive scalar fields allow for significant deviations from general relativity.

Abstract

Binary pulsar observations and gravitational wave detections seriously constrained scalar-tensor theories with massless scalar field allowing only small deviations from general relativity. If we consider a nonzero mass of the scalar field, though, significant deviations from general relativity are allowed for values of the parameters that are in agreement with the observations. In the present paper we extend this idea and we study scalar-tensor theory with massive field with self-interaction term in the potential. The additional term suppresses the scalar field in the neutron star models in addition to the effect of the mass of the scalar field but still, large deviations from pure GR can be observed for values of the parameters that are in agreement with the observations.