Are We Seeing Magnetic Axis Reorientation in the Crab and VELA Pulsars?
Abstract
Variation in the angle α between a pulsar's rotational and magnetic axes would change the torque and spin-down rate. We show that sudden increases in α, coincident with glitches, could be responsible for the persistent increases in spin-down rate that follow glitches in the Crab pulsar. Moreover, changes in α at a rate similar to that inferred for the Crab pulsar account naturally for the very low braking index of the Vela pulsar. If α increases with time, all pulsar ages obtained from the conventional braking model are underestimates. Decoupling of the neutron star liquid interior from the external torque cannot account for Vela's low braking index. Variations in the Crab's pulse profile due to changes in α might be measurable.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 1997
- DOI:
- 10.1086/310549
- arXiv:
- arXiv:astro-ph/9701096
- Bibcode:
- 1997ApJ...478L..91L
- Keywords:
-
- DENSE MATTER;
- MAGNETIC FIELDS;
- STARS: MAGNETIC FIELDS;
- STARS: NEUTRON;
- STARS: PULSARS: INDIVIDUAL NAME: CRAB PULSAR;
- STARS: PULSARS: INDIVIDUAL NAME: VELA PULSAR;
- Dense Matter;
- Magnetic Fields;
- pulsars: individual (Crab);
- pulsars: individual (Vela);
- Stars: Magnetic Fields;
- Stars: Neutron;
- Astrophysics
- E-Print:
- 14 pages and one figure, Latex, uses aasms4.sty. Accepted to ApJ Letters