Thermal Evolution of Magnetars under f(R, T) Gravity

Abstract

The present study explores the thermal evolution and emission properties of neutron stars within the framework of modified $f(R, T)$ gravity by solving the coupled energy-balance and heat-transport equations. We compute stellar mass and pressure profiles by solving the Tolman-Oppenheimer-Volkoff equations in both Einstein gravity and modified gravity, employing the APR, FPS, and SLy equations of state, with and without the strong magnetic field. Using these profiles, we assess the red-shifted surface temperature, $T_s^{\infty}$, as well as the photon and neutrino luminosities for each equation of state. We further examine the effects of the magnetic field, the choice of equation of state, and the underlying gravity theory framework on the cooling of neutron stars, particularly those of magnetized neutron stars or magnetars. Our results indicate that $f(R, T)$ gravity, particularly for the APR and SLy equations of state, exhibits improved agreement with the observed $T_s^{\infty}$ and photon luminosities than standard general relativity, regardless of magnetic-field strength. Moreover, it predicts the neutrino luminosities under both gravity models, all the chosen equations of state, and magnetic field configurations.

Figures (3)

• Figure 1: The variation of (a) red-shifted temperature ($T_s^\infty$), (b) red-shifted luminosity of photon ($L_\gamma^\infty$) and (c) red-shifted luminosity of neutrino ($L_\nu^\infty$) versus time for APR EoS with and without magnetic field. Observed data have also been shown for comparison.
• Figure 2: The variation of (a) red-shifted temperature ($T_s^\infty$), (b) red-shifted luminosity of photon ($L_\gamma^\infty$) and (c) red-shifted luminosity of neutrino ($L_\nu^\infty$) versus time for FPS EoS with and without magnetic field. Observed data have also been shown for comparison.
• Figure 3: The variation of (a) red-shifted temperature ($T_s^\infty$), (b) red-shifted luminosity of photon ($L_\gamma^\infty$) and (c) red-shifted luminosity of neutrino ($L_\nu^\infty$) versus time for SLy EoS with and without magnetic field. Observed data have also been plotted here for comparison.