Magnetic field decay in normal radio pulsars

TL;DR

This study investigates the magnetic field decay in normal radio pulsars, suggesting it primarily results from Ohmic decay due to phonon scattering, with a typical timescale of around 400,000 years.

Contribution

It provides evidence that magnetic field decay in pulsars is mainly caused by Ohmic decay on phonons, offering a clearer understanding of pulsar magnetic evolution.

Findings

Magnetic field decay timescale is approximately 4 x 10^5 years.

Decay is mainly due to Ohmic decay related to phonon scattering.

Hall effect may also influence the decay but is less dominant.

Abstract

We analyse the origin of the magnetic field decay in normal radio pulsars found by us in a recent study. This decay has a typical time scale $\sim 4 \times 10^5$~yrs, and operates in the range $\sim 10^5$~--~few$\times 10^5$~yrs. We demonstrate that this field evolution may be either due to the Ohmic decay related to the scattering from phonons, or due to the Hall cascade which reaches the Hall attractor. According to our analysis the first possibility seems to be more reliable. So, we attribute the discovered field decay mainly to the Ohmic decay on phonons which is saturated at the age few$\times 10^5$~yrs, when a NS cools down to the critical temperature below which the phonon scattering does not contribute much to the resistivity of the crust. Some role of the Hall effect and attractor is not excluded, and will be analysed in our further studies.