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

摘要

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