White dwarf structure in $f(R,T,L_m)$ gravity: beyond the Chandrasekhar mass limit

Abstract

In this work, we investigate the relativistic structure of white dwarfs (WDs) within the framework of modified gravity theory $f(R,T,L_m)=R+\alpha T{L}_m$, which introduces a non-minimal coupling between matter and curvature. Using a realistic equation of state (EoS) that includes contributions from a relativistic degenerate electron gas and ionic lattice effects, we solve the modified Tolman-Oppenheimer-Volkoff (TOV) equations for two standard choices of the matter Lagrangian density: $L_m=p$ and $L_m=-\rho$. We show that the extra $\alpha T{L}_m$ term significantly alters the mass-radius relation of WDs, especially at high central densities $({\rho }_c\gtrsim 10^8-10^{9}g/c{\mathrm{m}}^3)$, allowing for stable super-Chandrasekhar configurations. In particular, depending on the sign and magnitude of the parameter $\alpha$, the maximum mass can increase or decrease, and in some regimes, the usual critical point indicating the transition from stability to instability disappears. Our findings suggest that $f(R,T,L_m)$ gravity provides a viable framework to explain the existence of massive WDs beyond the classical Chandrasekhar limit. Using Bayesian inference with WD observational data, we further constrain the coupling parameter $\alpha$ for the two choices of the Lagrangian density $L_m$.

11 pages, 5 figures and 1 table. To appear in Physics Letters B

References in corpus (26)

• Unified cosmic history in modified gravity: from F(R) theory to Lorentz non-invariant models
• f(R,T) gravity
• Resummation of Massive Gravity
• f(R,L_m) gravity
• The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-mass white dwarf star
• The Luminous and Carbon-Rich Supernova 2006gz: A Double Degenerate Merger?
• Modified theories of Gravity: Why, How and What?
• New mass limit for white dwarfs: super-Chandrasekhar type Ia supernova as a new standard candle
• Stellar equilibrium configurations of white dwarfs in the $f(R,T)$ gravity
• A highly magnetised and rapidly rotating white dwarf as small as the Moon
• Generalizing the coupling between geometry and matter: $f(R,L_m,T)$ gravity
• Strongly magnetized cold electron degenerate gas: Mass-radius relation of the magnetized white dwarf
• Maximum mass of stable magnetized highly super-Chandrasekhar white dwarfs: stable solutions with varying magnetic fields
• Neutron stars in $f(R,L_m,T)$ gravity
• Modified Einstein's gravity as a possible missing link between sub- and super-Chandrasekhar type Ia supernovae
• Stability criterion for white dwarfs in Palatini $f(R)$ gravity
• Astrophysical Implications of a New Dynamical Mass for the Nearby White Dwarf 40 Eridani B
• Non-minimal geometry-matter couplings in Weyl-Cartan space-times: $f(R,T,Q,T_m)$ gravity
• One possible solution of peculiar type Ia supernovae explosions caused by a charged white dwarf
• Anisotropic quark stars in $f(R,L_m,T)$ gravity
• Metric-affine effects in crystallization processes of white dwarfs
• Anisotropic magnetized white dwarfs: Unifying under- and over-luminous peculiar and standard type Ia supernovae
• On the Maximum Mass of General Relativistic Uniformly Rotating White Dwarfs
• Weak-field limit of $f(R)$ gravity to unify peculiar white dwarfs
• Moment of inertia and compactness of quark stars within the context of $f(R,T,L_m)$ gravity
• White dwarfs in regularized 4D Einstein-Gauss-Bonnet gravity