Magnetic Field Topology in Pulsars
Abstract
The location of the spin-up line in the P - P diagram is shown to be sensitive to the presence of large-scale magnetic anomalies, and the surface strength of such fields can be constrained to be not more than approximately 40 percent of the surface strength of the dipole in spun-up pulsars. This constraint shows that if gamma-ray bursters are related to old Galactic neutron stars, those with strong cyclotron lines cannot have had the same magnetic history as spun-up millisecond pulsars. The spin-up line also constrains models in which the magnetic field is a single intense surface pole, although the present data set has too few very short period pulsars with measured P to provide useful information. As in some magnetic evolution scenarios, the spin-up line is insensitive to magnetic fields in which the dipole is formed by the superposition of many crustal clumps. However, polarization and beaming morphology of the radio emission in longer period pulsars can be used to argue that the near-zone fields of normal pulsars are not composed of such magnetic hair and could be used in the millisecond pulsars.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1993
- DOI:
- 10.1086/172576
- Bibcode:
- 1993ApJ...408..160A
- Keywords:
-
- Pulsars;
- Stellar Magnetic Fields;
- Stellar Magnetospheres;
- Stellar Physics;
- Topology;
- Accretion Disks;
- Gamma Ray Bursts;
- Neutron Stars;
- Astrophysics;
- GAMMA RAYS: BURSTS;
- STARS: PULSARS: GENERAL;
- STARS: MAGNETIC FIELDS;
- STARS: NEUTRON