Multifrequency Observations of the Crab Pulsar
D. A. Moffett & T. H. Hankins
Previously unseen profile components of the Crab pulsar have been
discovered in a study of the frequency-dependent behavior of its
average pulse profile between 0.33 and 8.4 GHz. One new component,
36 degrees ahead of the main pulse at 1.4 GHz, is not
coincident with the position of the precursor at lower frequencies.
Two additional, flat-spectrum components appear after the interpulse
between 1.4 and 8.4 GHz. The normal interpulse undergoes a
transition in phase and spectrum by disappearing near 2.7 GHz, and
reappearing 10 degrees earlier in phase at 4.7 and 8.4 GHz with a new
spectral index. The radio frequency main pulse disappears
for f > 4.9 GHz,
even though it is seen at infrared, optical, and higher energies.
The existence of the additional components at high frequency
and the strange,
frequency-dependent behavior is unlike anything seen in other
pulsars, and cannot easily be explained by emission from a simple
dipole field geometry.
STATUS: Ap.J., 468, 779.
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