The Crab Pulsar at Centimeter Wavelengths II: Single Pulses

TL;DR

This study presents high-frequency, high-time-resolution observations of the Crab pulsar, revealing two distinct emission mechanisms: nanoshot emission at lower frequencies and spectral band emission at higher frequencies, with implications for pulsar physics.

Contribution

It provides the first detailed characterization of single pulses across a broad frequency range, identifying two different emission physics operating in the Crab pulsar.

Findings

Main Pulses and Low-Frequency Interpulses show nanoshot emission with polarization.

High-Frequency Interpulses exhibit spectral band emission with linear polarization.

The emission physics of the longer-duration High-Frequency Component pulses remains uncertain.

Abstract

We have carried out new, high-frequency, high-time-resolution observations of the Crab pulsar. Combining these with our previous data, we characterize bright single pulses associated with the Main Pulse, both the Low-Frequency and High-Frequency Interpulses, and the two High-Frequency Components. Our data include observations at frequencies ranging from 1 to 43 GHz with time resolution down to a fraction of a nanosecond. We find at least two types of emission physics are operating in this pulsar. Both Main Pulses and Low-Frequency Interpulses, up to about 10 GHz, are characterized by nanoshot emission - overlapping clumps of narrow-band nanoshots, each with its own polarization signature. High-Frequency Interpulses, between 5 and 30 GHz, are characterized by spectral band emission - linearly polarized emission containing about 30 proportionately spaced spectral bands. We cannot say whether the longer-duration High-Frequency Component pulses are due to a scattering process, or if they come from yet another type of emission physics.