Neutron Star Structure in Poincaré Gauge Gravity with Quadratic Torsion
Researchers studied how neutron stars behave in Poincaré gauge gravity, a modified theory of gravity that includes torsion (spacetime twisting) effects. The theory predicts that torsion corrections make neutron stars more compact and lower their maximum mass compared to Einstein's general relativity. This work bridges alternative gravity theories with observational constraints from neutron star measurements.
A new theoretical study examines neutron star structure within Poincaré gauge gravity, an extension of general relativity incorporating quadratic torsion invariants. Using a Weyssenhoff fluid model with the Frenkel condition, the researchers reduced the field equations to modified Tolman-Oppenheimer-Volkoff equations that include spin-squared corrections to the effective energy density and pressure. Numerical solutions using the DD2 equation of state show that positive effective spin-spin coupling makes stellar configurations more compact, reduces maximum mass, and lowers binding energy compared to general relativity. Notably, unlike Einstein-Cartan theory, the spin-spin interaction coefficient is not fixed but depends on dimensionless quadratic-torsion coupling parameters. The analysis considers both isotropic and anisotropic spin correlations, though anisotropy effects on the mass-radius relation proved negligible for the weak-polarization profiles examined.
What's missing
The study does not discuss observational tests or constraints from existing neutron star mass-radius measurements that could validate or rule out the predicted deviations from general relativity. Additionally, the implications for gravitational wave signals from neutron star mergers or other observational signatures are not addressed.
What different sources said
- arXiv astro-phCenter
Neutron stars in Poincar\'e gauge gravity with quadratic torsion
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