Magnetic-oscillation Mechanism for Understanding Timing Noise of Pulsar Observation

Abstract

Highly precise pulsar timing is very important for understanding the nature of a neutron star, and it can even be used to detect gravitational waves. Unfortunately, the accuracy of the pulsar timing is seriously affected by the spin-down irregularities of pulsars, such as spin fluctuations with a manifestation of low frequency structures (the so-called red noise processes), and various activities of magnetospheres. The physical origins of these noises still remain unexplained. In this Letter, we propose a possible physical mechanism that the de Haas-van Alphen magnetic oscillation should trigger the observed low frequency structures in pulsar timing noises. We find that the de Haas-van Alphen magnetic oscillation period is about 1-\(10^{2}\) yr, which is about \(10^{-4}\) times as long as the classical characteristic time scale of the interior magnetic field evolution for a normal neutron star. Due to the de Haas-van Alphen magnetic oscillation, we estimate that the braking index can be between \(10^{-5}\) and \(10^{5}\), the range of residuals is between 10 ms to 820 ms for some quasi-periodic pulsars. Those are consistent with the pulsar timing observations.