Neutron stars in gravity
Phys. Rev. D 114, 024019 – Published 8 July, 2026
DOI: https://doi.org/10.1103/dy3t-1sq3
Abstract
We investigate the challenges of constructing neutron star (NS) solutions in gravity, highlighting the importance of treating the affine connection as an active, dynamical component of the theory. We begin by clarifying under what conditions standard simplifications—such as the coincident gauge or general relativity (GR)-like connections—inadvertently lead to GR behavior, even in nontrivial models. Building on previous work in black hole spacetimes, we adapt the formalism to NS and extend it to nonvacuum configurations. Focusing on two representative models, and , our analysis suggests that, under standard regularity assumptions, solutions with Maclaurin/Laurent-type series recover GR dynamics, pointing to more intricate structures as the likely seat of beyond-GR effects, and reflecting the constraints imposed by the connection’s dynamics on the asymptotic behavior of genuinely beyond-GR solutions. We then formulate the problem as a boundary value problem and highlight the numerical pathologies that may arise, together with possible strategies to prevent them. This work aims to provide a concrete framework for future numerical studies and outlines the theoretical consistency conditions required to construct physically meaningful beyond-GR NS solutions in gravity.