9 research outputs found
Short-lived Radio Bursts from the Crab Pulsar
Our high-time-resolution observations reveal that individual main pulses from
the Crab pulsar contain one or more short-lived microbursts. Both the energy
and duration of bursts measured above 1 GHz can vary dramatically in less than
a millisecond. These fluctuations are too rapid to be caused by propagation
through turbulence in the Crab Nebula or the interstellar medium; they must be
intrinsic to the radio emission process in the pulsar. The mean duration of a
burst varies with frequency as , significantly different from the
broadening caused by interstellar scattering. We compare the properties of the
bursts to some simple models of microstructure in the radio emission region.Comment: 34 pages, 10 figures; accepted for publication in Ap
Polarimetric Properties of the Crab Pulsar between 1.4 and 8.4 GHz
New polarimetric observations of the Crab pulsar at frequencies between 1.4
and 8.4 GHz are presented. Additional pulse components discovered in earlier
observations (Moffett & Hankins 1996, astro-ph/9604163) are found to have high
levels of linear polarization, even at 8.4 GHz. No abrupt sweeps in position
angle are found within pulse components; however, the position angle and
rotational phase of the interpulse do change dramatically between 1.4 and 4.9
GHz. The multi-frequency profile morphology and polarization properties
indicate a non-standard origin of the emission. Several emission geometries are
discussed, but the one favored locates sites of emission both near the pulsar
surface and in the outer magnetosphere.Comment: 20 pages, 7 postscript figures, uses aaspp4 Latex style. To appear in
Volume 522 of The Astrophysical Journa