Nature of anomalous X-ray pulsars, soft gamma repeaters and radio pulsars with very long periods
Abstract:A brief review of the known models for the description of anomalous X-ray pulsars (AXPs) and soft gamma repeaters (SGRs) is given. A new model is proposed to explain the main properties of these objects on the basis of the concept of drift waves in the vicinity of the light cylinder of the neutron star with a surface magnetic field of about 10 12 G. In the framework of this model, the rotation periods P , their derivatives d P /d t and the magnetic fields B in the regions of generation of emission observed in AXPs and SGRs are calculated. The intervals for these parameters are P = 11 − 737 ms, d P /d t = 3.7 × 10 − 16 − 5.5 × 10 − 12 and log B = 2.63 − 6.25. A modulation with periods P could be observed in the sources under consideration. The magnetic fields at the neutron star's surface calculated in the framework of the dipole model for AXPs and SGRs have the same order (〈log B s 〉 = 11.90) as for normal radio pulsars. Pulsars of the types under consideration must have short periods ( P ≈ 0.1 s) and a small angle between the rotation and magnetic axes ( 4 s). The model under consideration allows us to calculate the real rotation periods of host neutron stars. They are of the order of 1 s for the investigated objects. The magnetic fields at the surface of the neutron star are of the order of 10 11 –10 13 G and equal to the fields usual for normal radio pulsars.
Document Type: Research Article
Affiliations: 1: Pushchino Radio Astronomy Observatory, P.N. Lebedev Physical Institute, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia 2: Abastumani Astrophysical Observatory, Al. Kazbegi Avenue 2a, 380060, Tbilisi, Georgia
Publication date: February 1, 2006