STANFORD UNIVERSITY
EE 350 RADIOSCIENCE SEMINAR
Professor Umran S. Inan

Winter 1998-99

Date: Wednesday, February 17, 1999
Time: 4:15-5:30 PM; Refreshments at 4:00 PM
Location: GESB 124


Recent Activity of the Crab Nebula Pulsar

Prof. Donald Backer
UC Berkeley

Abstract

Pulsars are rapidly rotating, highly magnetized neutron stars that form in the implosion/explosion of massive stars which have exhausted their nuclear fuel. The Crab Nebula and pulsar are the remains of an event in AD 1054. The pulsar spins at about 30 Hz and emits narrow beams of radio-Gamma ray emission that we detect as pulses as a consequence of rotation. The emission processes are still cloaked in the difficulty of analysis of this extreme electrodynamic system.

During the past couple years this pulsar has been unusually active. Timing the arrival of its pulses shows the effects of rotational energy loss which is result of magnetic dipole radiation and currents. Superimposed on this slowdown are sudden events, glitches, which result from sudden changes of the internal structure. In the past two years a swarm of glitches have been detected with our pulsar monitoring telescope in Green Bank, WV. Unrelated to the glitches is activity in the effects on signal propagation incurred as it passes through the filamentary network of thermal plasma that surrounds the relativistic bubble of plasma in the Crab Nebula, dispersion and scattering. Finally I will describe investigations of giant radio pulses emitted by the pulsar that are aimed at exploring properties of the emission mechanism.