A Low Frequency Survey of Giant Pulses from the Crab Pulsar

TL;DR

This study conducts a comprehensive low-frequency survey of giant pulses from the Crab Pulsar using the Long Wavelength Array, analyzing pulse characteristics, detection methods, and scattering effects over multiple epochs.

Contribution

It introduces automated detection methods for giant pulses at low frequencies and provides the first extensive multi-epoch analysis of scattering effects on these pulses.

Findings

Flux density increases at shorter wavelengths, indicating a spectral turnover at 100 MHz.

Detected over 1400 pulses across four frequency bands, with some observed simultaneously.

Variations in detection rates reflect changes in scattering due to the interstellar medium.

Abstract

We present a large survey of giant pulses from the Crab Pulsar as observed with the first station of the Long Wavelength Array. Automated methods for detecting giant pulses at low frequencies where scattering becomes prevalent are also explored. More than 1400 pulses were detected across four frequency bands between 20 - 84 MHz over a seven month period beginning in 2013, with additional followup observations in late 2014 and early 2015. A handful of these pulses were detected simultaneously across all four frequency bands. We examine pulse characteristics, including pulse broadening and power law indices for amplitude distributions. We find that the flux density increases toward shorter wavelengths, consistent with a spectral turnover at 100 MHz. Our observations uniquely span multiple scattering epochs, manifesting as a notable trend in the number of detections per observation. These results are characteristic of the variable interface between the synchrotron nebula and the surrounding interstellar medium.