Correlation of Chandra photons with the radio giant pulses from the Crab pulsar

TL;DR

This study found no significant correlation between radio giant pulses and X-ray photons from the Crab pulsar, suggesting plasma coherence changes may underlie giant pulse phenomena.

Contribution

The paper provides the first simultaneous radio and X-ray observations of the Crab pulsar, setting upper limits on X-ray flux variations during giant pulses.

Findings

No significant X-ray flux change during GPs within 10-30% limits.

X-ray flux during GPs does not exceed a factor of 2-5 increase.

Results support plasma coherence changes as the origin of GPs.

Abstract

No apparent correlation was found between giant pulses (GPs) and X-ray photons from the Crab pulsar during 5.4 hours of simultaneous observations with the Green Bank Telescope at 1.5 GHz and Chandra X-Ray Observatory primarily in the energy range 1.5-4.5 keV. During the Crab pulsar periods with GPs the X-ray flux in radio emission phase windows does not change more than by +-10% for main pulse (MP) GPs and +-30% for interpulse (IP) GPs. During giant pulses themselves, the X-ray flux does not change more than by two times for MP GPs and 5 times for IP GPs. All limits quoted are compatible with 2-sigma fluctuations of the X-ray flux around the sets of false GPs with random arrival times. The results speak in favor of changes in plasma coherence as the origin of GPs. However, the results do not rule out variations in the rate of particle creation if the particles that emit coherent radio emission are mostly at the lowest Landau level.