Compact star in noninteger power model of $f(R)$ gravity

TL;DR

This paper explores how noninteger power $f(R)$ gravity models affect the structure of compact stars, revealing significant deviations from general relativity in mass-radius relations and demonstrating effective scalar field screening mechanisms.

Contribution

It introduces the NIP $f(R)$ gravity model's impact on compact star properties and shows the chameleon mechanism's role in scalar field screening.

Findings

Large deviations in mass-radius relations from GR in low-mass stars.

Efficient scalar hair screening via the chameleon mechanism.

Distinct scalar profiles inside and outside stars.

Abstract

We investigate compact stars in the noninteger power (NIP) model of $f(R)$ gravity theory, which includes the higher-curvature correction to the Einstein-Hilbert action. The mass-radius relation of the compact stars in the NIP model predicts large deviations from those in the general relativity in the low-mass region, potentially allowing us to test the NIP model by future astrophysical observations. We also study the nonvanishing scalar hair surrounding the compact star and demonstrate that the chameleon mechanism works efficiently. They result in distinct scalar profiles inside and outside the star, which implies screening the fifth force mediated by the scalar field.