Phase Offset of Rotation-Powered X-ray Pulsars

Combing the data of all the 10 rotation-powered pulsars that have measurements of relative phase of radio and X-ray pulses, we report here the behavior of radio/X-ray phase offset. We find that the radio/X-ray offset of normal pulsars does not show the trend of increase with increasing pulsar period as the radio/gamma-ray offset exhibits. The offset of millisecond pulsars is generally much less than that of the normal pulsars. Such phenomenon should also be taken into account by the high energy models for pulsars.

Pulsar Profiles and Structure of the Emission Region

Recent radio observations of pulsar profiles and the present knowledge about structure of the emission region based on this profiles data are reviewed.Observations and component structure analysis revealed that there are pulsars profiles having more than 5 components. It call into question that the commonly adopted model of emission region as the double hollow cones and a central core is applicable. Mosaic model of an emission region fit observed profiles with complex more than 5 component structure.The height (radius) for the emission region evaluated from a dependence of a width of integrated profiles from the pulsar period is estimated asrem≅ 1.5 × l07P0.1cm.A comparative analysis of the frequency dependence of the profile widths of millisecond and normal pulsars in 0.1 to 1.4 GHz frequency range indicates that the frequency dependence of a width of their profiles, is much weaker than what is typically observed for normal pulsars. This suggests that the geometry of the emission region of millisecond pulsars is unlike that of normal ones.

Development of K4 Correlator for Pulsar VLBI: Japan-Russia Baseline

We are doing astrometric pulsar VLBI observation with Kashima-Kalyazin 7000 km baseline. K4 correlator is under the development for this observation program. When XF type correlator is used for pulsar processing with gating, attention should be paid to avoid fluctuation on delay result due to fractional bit effect. This influence is serious around the point that bit shift for delay tracking and pulsar period is synchronized. In this paper, the K4 correlation system is introduced and fractional bit effect on pulsar processing is explained.

The investigations of pulsar integral radio luminosities

We have calculated accurate integral radio luminositiesLfor 232 pulsars (Malov et al., 1994) using new average spectra of these objects. Histogram ofL-distribution is characterized by the mean value < logL>= 28.45 and by the mean-square-root deviationS= 1.0. We have analysed also data for short-periodic pulsars (P < 0.1 s) and long-periodic ones (P > 1 s) separately.The main goal of such separation was to test the hypothesis on two types of pulsars (Malov, 1987): i) for the first group of objects radiation is emitted from the neighbourhood of the light cylinder (r=rLC=cP/2π, P is the pulsar period), ii) for the second one emission is generated at distancesr≪rLC. In the second case the main mechanism of radiation is curvature radiation. For the first group of pulsars the radiation is connected with the cyclotron mechanism. The difference between two basic mechanisms and the locations of the emission generation regions must cause some differences in the observable features for these two classes of pulsars.

Very High Energy Emission from Pulsars

Observations of gamma rays around 1012eV (= 1 TeV) from pulsars are reviewed and the results are discussed and compared with emission at other wavelengths. Very high energy gamma rays do not appear to be modulated with the pulsar period, which suggests that a major part of the VHE emission is not from the pulsar magnetosphere.