Bright Giant Pulses from the Crab Nebula Pulsar: Statistical Properties, Pulse Broadening, and Scattering Due to the Nebula

Abstract

We report observations of Crab giant pulses made with the Australia Telescope Compact Array and a baseband recorder system, made simultaneously at two frequencies, 1300 and 1470 MHz. These observations were sensitive to pulses with amplitudes \ga 3 kJy and widths \ga 0.5 $\mu$s. Our analysis led to the detection of more than 700 such bright giant pulses over 3 hours, and using this large sample we investigate their amplitude, width, arrival time and energy distributions. The brightest pulse detected in our data has a peak amplitude of $\sim$ 45 kJy and a width of $\sim$ 0.5 $\mu$s, and therefore an inferred brightness temperature of $\sim 10^{35}$ K. The duration of giant-pulse emission is typically $\sim$1 $\mu$s, however it can also be as long as 10 $\mu$s. The pulse shape at a high time resolution (128 ns) shows rich diversity and complexity in structure and is marked by an unusually low degree of scattering. We discuss possible implications for scattering due to the nebula, and for underlying structures and electron densities.