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

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--one may hope to probe the dense matter equation of state. In this work, we explore, within a highly idealized three-component framework, whether the glitch rise could in principle carry information about microphysical inputs such as entrainment and mutual friction. We compute the glitch rise in response to self-consistently calculated microphysical parameters (pinning and mutual friction) based on unified equations of state, and compare theoretical predictions of the overshoot patterns and timing residuals to the 2016 Vela glitch. Within this specific framework, the models favor crustal superfluid coupling on timescales of order $\sim 100$ s, overshoot behavior in the core associated with relatively strong central mutual friction, and rise times consistent with the observed upper limit of 12.6 s. Using a Markov Chain Monte Carlo analysis of the timing residuals, we then map the regions of parameter space that are compatible with the data under our adopted assumptions. Our analysis favors comparatively weak entrainment in the inner crust and an overall core mutual friction that is weaker than that in the inner crust. These exploratory results demonstrate that, under such restrictive assumptions, glitch-rise morphology is sensitive to microphysical inputs and that future high-cadence timing observations, interpreted with more realistic dynamical models, could potentially help constrain the internal dynamics and composition of neutron stars.

Comments: 15 pages, 10 figures, 4 tables; version accepted for publication in 2016 ApJ 1007 118