Long-Term X-ray Monitoring of the Young Pulsar PSR B1509-58

TL;DR

This study presents a 14.7-year analysis of the young pulsar PSR B1509-58, demonstrating stable pulsed X-ray flux, pulse profile, and no magnetar-like bursts, supporting long-term stability of rotation-powered pulsar X-ray properties.

Contribution

It provides the first long-term systematic analysis of PSR B1509-58's X-ray properties, extending timing data and constraining variability and burst rates over decades.

Findings

Pulsed X-ray flux is stable over 14.7 years.

No magnetar-like bursts detected, limiting burst rate.

Pulse profile remains consistent over days to decades.

Abstract

It has long been thought that the pulsed X-ray properties of rotation-powered pulsars are stable on long time scales. However, long-term, systematic studies of individual sources have been lacking. Furthermore, dramatic X-ray variability has now been observed from two pulsars having inferred sub-critical dipole magnetic fields. Here we present an analysis of the long-term pulsed X-ray properties of the young, energetic pulsar PSR B1509-58 using data from the Rossi X-ray Timing Explorer. We measured the 2-50 keV pulsed flux for 14.7 yr of X-ray observations and found that it is consistent with being constant on all relevant time scales, and place a 3 sigma upper limit on day-to-week variability of <28%. In addition, we searched for magnetar-like X-ray bursts in all observations and found none, which we use to constrain the measurable burst rate to less than one per 750 ks of observations. We also searched for variability in the pulse profile and found that it is consistent with being stable on time scales of days to decades. This supports the hypothesis that X-ray properties of rotation-powered X-ray pulsars can be stable on decade-long time scales. In addition, we extend the existing timing solution by 7.1 yr to a total of 28.4 yr and report updated values of the braking index, n=2.832+/-0.003 and the second braking index, m=17.6+/-1.9.