Evolution of Urca Pairs in the Crusts of Highly Magnetized Neutron Stars

TL;DR

This paper investigates how strong magnetic fields influence neutrino emission via the modified Urca process in neutron star crusts, revealing effects on emission spectra and angular asymmetry, especially at high field strengths.

Contribution

It introduces a detailed analysis of Landau level effects on Urca pairs and neutrino emission in highly magnetized neutron stars, highlighting new spectral features and asymmetries.

Findings

Landau levels significantly alter neutrino emission spectra at high magnetic fields.

Neutrino emission becomes angularly asymmetric due to magnetic field effects.

Strong magnetic fields cause dramatic spikes in the emission spectrum when electrons are confined to a single Landau level.

Abstract

We report on the effects of strong magnetic fields on neutrino emission in the modified Urca process. We show that the effect of Landau levels on the various Urca pairs affects the neutrino emission spectrum and leads to an angular asymmetry in the neutrino emission. For low magnetic fields the Landau levels have almost no effect on the cooling. However, as the field strength increases, the electron chemical potential increases resulting in a lower density at which Urca pairs can exist. For intermediate field strength there is an interesting interference between the Landau level distribution and the Fermi distribution. For high enough field strength, the entire electron energy spectrum is eventually confined to single Landau level producing dramatic spikes in the emission spectrum.