Red Noise in Anomalous X-ray Pulsar Timing Residuals

TL;DR

This paper introduces a method to quantify low-frequency timing noise in Anomalous X-ray Pulsars, revealing insights into their spin-down irregularities by analyzing observational data from multiple pulsars.

Contribution

It presents a new procedure for extracting the intensity and spectral index of timing noise in AXPs, addressing challenges posed by low-frequency components.

Findings

Quantified timing noise in five AXPs and five young pulsars.

Identified strong low-frequency components in AXP timing noise.

Compared noise characteristics across different pulsar types.

Abstract

Anomalous X-ray Pulsars (AXPs), thought to be magnetars, exhibit poorly understood deviations from a simple spin-down called "timing noise". AXP timing noise has strong low-frequency components which pose significant challenges for quantification. We describe a procedure for extracting two quantities of interest, the intensity and power spectral index of timing noise. We apply this procedure to timing data from three sources: a monitoring campaign of five AXPs, observations of five young pulsars, and the stable rotator PSR B1937+21.