Possible existence of super Chandrasekhar mass limit in the matter-curvature coupled gravity

TL;DR

This paper explores modified gravity theories to show that white dwarfs can have masses exceeding the classical Chandrasekhar limit, with implications for supernovae and stellar evolution.

Contribution

It introduces new models of f(R,L_m) and f(R,L_m,T) gravity that allow for super-Chandrasekhar white dwarfs, extending beyond classical limits.

Findings

White dwarf mass limit can reach up to 1.537 M_sun in f(R,L_m,T) gravity.

Modified gravity models predict lower compactness and gravitational redshift than neutron stars.

Stability analysis confirms the viability of super-Chandrasekhar white dwarfs in these models.

Abstract

We investigate white dwarfs in the framework of f(R,L_m) and f(R,L_m,T) gravity to explore the Chandrasekhar Limit. We have considered two functional forms of f(R,L_m) and one functional form of f(R,L_m,T) gravity. Considering the matter Lagrangian L_m=p, we calculate modified TOV equations for each of the forms. By employing the fully degenerate electron gas equation of state in the modified TOV equations, we derive the mass-radius relation for each functional form of both f(R,L_m) and f(R,L_m,T) gravity. Our models imply modifications in the Chandrasekhar mass limit that deviate significantly from the GR and the Newtonian cases. In the f(R,L_m, T)$ gravity, the new mass limit of the white dwarf can reach upto 1.537\,\mathrm{M}_\odot while in f(R,L_m) with the quadratic extension can goes upto 1.52\,\mathrm{M}_\odot and with exponential extension upto 2.08\,\mathrm{M}_\odot. Further, we analyze the static stability criterion, the gravitational redshift, and the adiabatic indices. For the power-law form of f(R,L_m) and the non-linear form of f(R,L_m,T) gravity, significant variations are observed at higher densities (\rho_c > 10^{10}\, \mathrm{g/cm^3}), while substantial changes are noted at much lower central densities in the case of exponential form of f(R,L_m) gravity. We also calculate compactness and gravitational redshift, which are much lower than those of neutron stars and black holes. Stability is also confirmed by adiabatic indices, which show that all models yield \Gamma > 4/3 throughout the interiors of WDs. Overall, our models provide a viable framework for the existence of super-Chandrasekhar mass limit, extending beyond the classical predictions in the Newtonian and/or GR cases.