Variations of the harmonic components of the X-ray Pulse Profile of PSR B1509-58

TL;DR

This study analyzes 15 years of X-ray pulse profiles of PSR B1509-58 using Fourier decomposition to assess the stability of harmonic components, aiding understanding of pulsar physics and potential navigation applications.

Contribution

It provides a detailed long-term analysis of harmonic stability in the X-ray pulse profile of PSR B1509-58, a novel application of Fourier techniques over such an extended period.

Findings

Harmonic amplitudes are stable over 15 years.

No significant variation in harmonic phases observed.

Harmonic amplitudes are approximately 37%, 13%, and 9% of the fundamental.

Abstract

We used the Fourier decomposition technique to investigate the stability of the X-ray pulse profile of a young pulsar PSR B1509-58 by studying the relative amplitudes and the phase differences of its harmonic components with respect to the fundamental using data from the Rossi X-Ray Timing Explorer. Like most young rotation powered pulsars, PSR B1509-58 has a high spin down rate. It also has less timing noise allowing accurate measurement of higher order frequency derivatives which in turn helps in study of the physics of pulsar spin down. Detailed investigation of pulse profiles over the years will help us establish any possible connection between the timing characteristics and the high energy emission characteristics for this pulsar. Further, the study of pulse profiles of short period X-ray pulsars can also be useful for using them as means of interplanetary navigation system. The X-ray pulse profile of this source has been analysed for 15 $ \rm years $ (1996-2011). The long term average amplitudes of the first, second and third harmonics (and their standard deviation for individual measurements) compared to the fundamental are 36.9 % (1.7 %), 13.4 % (1.9 %) and 9.4 % (1.8 %) respectively. Similarly, the phases of the three harmonics (and standard deviations) with respect to the fundamental are 0.36 (0.06), 1.5 (0.2), 2.5 (0.3) $\rm radian $ respectively. We do not find any significant variation of the harmonic components of the pulse profile in comparison to the fundamental.