A Study On The Polar Cap Geometry Of PSR B1259-63

This thesis introduced the works accomplished during my graduate study period. These works included the discussion on the progress of observational research of rotating radio transients, and the study on the polar cap geometry of PSR B1259-63. The main work is focused on the determining the pulsar magnetic inclination angleαand the angleβbetween the line of sight and the magnetic axis. These two are most important parameters of pulsar radiation cone. In general, the angleαandβcan not be obtained directly by the observation, they only be obtained by the geometry research of polar cap model and statistical analysis. The determination of these two parameters is important to establish the structure of the pulsar magnetosphere and radiation mechanisms.In Chapter 2, the discussion on the recent progress of observational research of Rotating Radio Transients(RRATs) are introduced. RRATs are a special class of radio sources. Compared with ordinary pulsars, they have the following characteristics: repeating millisecond timescale dispersed bursts and without periodic impulsive. As a result, it is very difficult to detect this kind of radio source. At present there were approximately 46 type of rotating radio transient sources been found, among which 27 have been confirmed the second grade periods, 7 were measured of its period derivatives. This paper mainly introduces some properties of the seven RRATs which have already measured period derivatives, and the relations and differences with other several known types of neutron stars.In the third chapter describes the study on the polar cap geometry of PSR B1259-63. We study the polar cap geometry of PSR B1259-63 by fitting the position angle data of the pulsar for rotating vector model (RVM). The observational data at 1.52 GHz, 4.68 GHz and 8.28 GHz used in this paper come from the European Pulsar Network Data Archive. Under the nearly-aligned-rotator assumption and nearly–orthogonal-rotator assumption, the least-squares algorithm fitting on the position angle data at three frequencies is carried out. In case of the assumption of nearly aligned rotator, the parameters for two models, i.e.α=10.0~0±0.5~0,β=0.5~0±0.3~0 for model (a) andα=36.3~0±2~0,β=9~0±2~0 for model (b), are obtained. Our results for the nearly-aligned-rotator assumption are consistent with that of Manchester and Johnston (1995). Under the assumption of nearly orthogonal rotator, we obtainαMP=83~0±2~0,βMP=-3~0±1~0 andαIP=97~0±1~0,βIP=-17~0±1~0 by fitting for the position angle data of the main pulse (MP) and the inter pulse (IP) respectively. In this case, the results indicated that the main pulse and inter pulse of the pulsar are likely to originated from two different magnetic poles, so the possibility of the pulsar is a nearly orthogonal rotator can not be excluded. The polar cap geometry of PSR B1259-63 can not be solved by fitting RVM to the observational data obtained so far. Further observations and studies are strongly suggested.The works included in this thesis are summarized in Chapter 4.