Magnetic field evolution of X-ray emitting radio-quiet pulsars

TL;DR

This paper investigates how magnetic fields in X-ray emitting radio-quiet neutron stars evolve over time, linking magnetic energy dissipation to observable properties like spin and thermal emission.

Contribution

It provides a theoretical analysis connecting magnetic field decay rates with observable spin and thermal properties in isolated neutron stars, highlighting the rapid decay timescale.

Findings

Magnetic energy dissipation correlates with spin period derivative evolution.

Magnetic field decay timescale is shorter than typical pulsar ages.

X-ray emission reflects magnetic energy release.

Abstract

The intense magnetic fields present in neutron stars are closely linked to their observed temperature and spectral characteristics, timing properties, including spin period and its derivatives. Therefore, a comprehensive theoretical analysis of magnetic field evolution is essential for understanding how the strength of the magnetic field change over time. The decay rate of magnetic field in isolated, non-accreting neutron stars can be assessed by evaluating the second derivative of the spin frequency. Another method to estimate this rate involves monitoring an increase in thermal emission beyond what is expected from standard cooling processes, assuming no additional heating mechanisms are present. Our findings indicate that for X-ray emitting isolated neutron stars, the evolution rate of spin period derivative aligns with the dissipation rate of magnetic energy from the dipolar field, provided that a substantial portion of the released energy is emitted as X-rays. The time scale of magnetic field decay is found to be much shorter than typical age of radio pulsars.