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° ahead of the main pulse at 1.4 GHz, is not coincident with the position of the precursor at lower frequencies. Two additional, fiat-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° earlier in phase between 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.
The Astrophysical Journal
- Pub Date:
- September 1996
- STARS: PULSARS: INDIVIDUAL NAME: CRAB PULSAR;
- RADIO CONTINUUM: STARS;
- 13 pages. Source is single LaTeX file with 3 figures, using aaspp and epsf style files (included). To appear in The Astrophysical Journal, September 1996. Paper can also be found at http://www.ee.nmt.edu/