Impact of modified gravity theory on neutron star and nuclear matter properties

TL;DR

This study explores how energy-momentum squared gravity (EMSG) influences neutron star properties, revealing deviations from general relativity in mass-radius relations and nuclear matter characteristics, but current data lack definitive evidence of such deviations.

Contribution

It provides a comprehensive analysis of EMSG effects on neutron star observables using various nuclear models and highlights the need for more precise data to confirm deviations from general relativity.

Findings

Neutron star mass-radius sequences differ in EMSG versus GR.

Effective nuclear equation of state shows notable variation in EMSG.

Current observational data do not conclusively confirm deviations from GR.

Abstract

New observational data, measured with a high degree of accuracy, of compact isolated neutron stars and binary stars in gravitational wave remnants have the potential to explore the strong field gravity. Within the framework of energy-momentum squared gravity (EMSG) theory we study its impact on several properties of neutron stars and plausible modifications from the predictions of general relativity. Based on a representative set of relativistic nuclear mean field models, non-relativistic Skyrme-Hartree-Fock models and microscopic calculations, we show deviations of neutron star mass-radius sequence in EMSG theory as compared to general relativity. The variation in the effective nuclear equation of state in EMSG, results in distinct magnitudes in the reduced pressure, speed of sound, and maximum compactness at the center of neutron stars. We perform extensive correlation analysis of the nuclear model parameters with the neutron star observables in light of the new observational bounds. Perceptible modifications in the correlations are found in the models of gravity that provide different estimates of the slope and curvature of nuclear matter symmetry energy. The available neutron star data however do not impose stringent enough constraints for clear evidence of deviations from general relativity.