A Microphysical Probe of Neutron Star Interiors: Constraining the Equation of State with Glitch Dynamics

TL;DR

This paper models neutron star glitch dynamics to constrain the dense matter equation of state, using microphysical parameters and observational data from the 2016 Vela glitch.

Contribution

It introduces a microphysical model of glitch dynamics incorporating vortex motion and mutual friction, and uses MCMC analysis to match observations, providing new insights into neutron star interiors.

Findings

Crustal superfluid couples in about 100 seconds

Observed overshoot behavior indicates strong crustal and weak core friction

Rise times are consistent with the 12.6-second observational upper limit

Abstract

Glitches in neutron stars originate from the sudden transfer of angular momentum between superfluid components and the observable crust. By modeling this glitch dynamics, including vortex motion, mutual friction, and angular momentum exchange, we can probe the dense matter equation of state. We match theoretical predictions of glitch rise times, overshoot patterns, and relaxation timescales to the well-documented observations of the 2016 Vela glitch. Our model incorporates microphysical parameters such as the mutual friction coefficient $\mathcal{B}$, which in the core arises from electron scattering off magnetized vortices, and in the crust from Kelvin wave excitation during vortex-lattice interactions. Our Markov Chain Monte Carlo analysis of the timing residuals reveals detailed glitch dynamics: the crustal superfluid couples on timescales of $\sim100$ seconds, the core exhibits overshoot behavior due to strong central behavior, and the inner crust shows weak entrainment, with $\sim70\%$ of free neutrons remaining superfluid. The modeled rise times are consistent with the observed upper limit of 12.6 seconds, and the observed overshoot requires strong crustal friction but weak core friction, supporting a spatially varying $\mathcal{B}$.These findings highlight the importance of microphysical modeling and demonstrate the potential of future high-cadence timing observations to further constrain the internal dynamics and composition of neutron stars.