Radio Emission Signatures in the Crab Pulsar

TL;DR

This study reveals distinct radio emission signatures in the Crab pulsar's main pulse and interpulse, with nanoshots likely caused by plasma turbulence and unique emission bands at centimeter wavelengths, challenging existing theories.

Contribution

It provides high-resolution observations showing different emission mechanisms for main pulse and interpulse, including the discovery of proportionately spaced emission bands.

Findings

Main pulses exhibit short-lived, narrow-band nanoshots.

Interpulses display regular, proportionately spaced emission bands.

Emission bands at 4.5 to 10.5 GHz are not explained by current theories.

Abstract

Our high time resolution observations of individual pulses from the Crab pulsar show that both the time and frequency signatures of the interpulse are distinctly different from those of the main pulse. Main pulses can occasionally be resolved into short-lived, relatively narrow-band nanoshots. We believe these nanoshots are produced by soliton collapse in strong plasma turbulence. Interpulses at centimeter wavelengths are very different. Their dynamic spectrum contains regular, microsecond-long emission bands. We have detected these bands, proportionately spaced in frequency, from 4.5 to 10.5 GHz. The bands cannot easily be explained by any current theory of pulsar radio emission; we speculate on possible new models.