Pulse profile stability of the Crab pulsar

TL;DR

This study analyzes a decade of RXTE X-ray data to assess the stability of the Crab pulsar's pulse profile across different energies, finding consistent phase, intensity, and width of the pulses over time.

Contribution

It provides the first comprehensive long-term analysis of pulse profile stability of the Crab pulsar in soft and hard X-ray energies.

Findings

Pulse profile remains stable over ten years.

The first pulse is stronger at soft X-rays.

The pulse peaks are stable in phase, intensity, and width.

Abstract

We present an X-ray timing analysis of the Crab pulsar, PSR B0531+21, using the archival RXTE data. We have investigated the stability of the Crab pulse profile, in soft (2-20 keV) and hard (30-100 keV) X-ray energies, over the last decade of RXTE operation. The analysis includes measurement of the separation between the two pulse peaks; and intensity and the widths of the two peaks. We did not find any significant time dependency in the pulse shape. The two peaks are stable in phase, intensity and widths, for the last ten years. The first pulse is relatively stronger at soft X-rays. The first pulse peak is narrower than the second peak, in both, soft- and hard X-ray energies. Both the peaks show a slow rise and a steeper fall. The ratio of the pulsed photons in the two peaks is also constant in time.