Exploring nuclear force with pulsar glitch observation

TL;DR

This paper investigates the connection between nuclear forces and pulsar glitches by modeling the inner crust of neutron stars using the Relativistic Mean Field approach, and compares theoretical pinning forces with observed glitch data.

Contribution

It introduces a detailed modeling of vortex pinning in neutron star crusts using RMF models, linking nuclear parameters to glitch phenomena.

Findings

Pinning force evolution matches observed glitch amplitudes.

Nuclear symmetry energy slope significantly influences pinning strength.

Refined nuclear models improve understanding of pulsar glitch mechanisms.

Abstract

We connect nuclear forces to one of the most notable irregular behaviors observed in pulsars, already detected in approximately 6\% known pulsars, with increasingly accurate data expected from upcoming high-precision timing instruments on both ground and space. Built on Shang & Li (2021), we conduct a case study on the 2001 glitch of the Vela pulsar. For our purpose, we adopt the Relativistic Mean Field (RMF) model as the theoretical many-body framework to describe nuclear systems. We refit three representative RMF parameter sets (DD-ME2, PKDD, NL3), considering the uncertainties in nuclear matter saturation properties. Utilizing the resulting star structure, composition and nucleon properties in the medium obtained in a consistent manner, we calculate the pinning energy of superfluid vortex in the nuclear lattice in the inner crust. This leads to the evolution of associated pinning force that acts on the vortex, which can be confronted with observed glitch amplitude and short-time relaxation in the 2000 Vela glitch event, following the snowplow model of pulsar glitch. We discuss how the vortex configuration and pinning properties depend on the nuclear parameters, and find an interesting and dominant role of the nuclear symmetry energy slope on pinning strength.