MAGNETIC-FIELD TOPOLOGY IN PULSARS

被引:89
作者
ARONS, J
机构
[1] UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720
[2] LAWRENCE LIVERMORE NATL LAB,INST GEOPHYS & PLANETARY PHYS,LIVERMORE,CA 94550
[3] LAWRENCE LIVERMORE NATL LAB,PLASMA PHYS RES INST,LIVERMORE,CA 94550
关键词
GAMMA-RAYS; BURSTS; PULSARS; GENERAL; STARS; MAGNETIC FIELDS; NEUTRON;
D O I
10.1086/172576
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
It is shown that the location of the spin-up line in the P - P diagram is sensitive to the presence of large-scale magnetic anomalies (quadrupole, ...) and that one can usefully constrain the surface strength of such fields to be not more than approximately 40% 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. The spin-up line is insensitive to magnetic fields in which the dipole is formed by the superposition of many crustal clumps, as in some magnetic evolution scenarios. 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, once data become available for a substantial number of these stars. An interesting byproduct of the analysis is the conclusion that if the disks confining the magnetospheres during the spin-up phase are largely diagmagnetic and entrain the stellar magnetic field only in a boundary layer whose thickness is comparable to that of the disk, the inner edges of such disks are located at the radius expected in spherical accretion. The fact that the resulting spin-up line for a dipolar magnetosphere agrees so well with the data is used to support the idea that the disk-magnetosphere interaction is fundamentally similar to that occurring between the solar wind and planetary magnetospheres, where in spite of the strong dissipation, the exterior plasma is dynamically excluded from the magnetosphere as if it is diamagnetic.
引用
收藏
页码:160 / 166
页数:7
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