We have calculated the probability of observing geodetic precession in the binary pulsar PSR1913+16 for several different progenitor systems. Such an observation would support the asymmetric kick hypothesis for the origin of pular velocities. The results are shown to be dependent on the assumed progenitor but not to a strong degree. It is concluded that the probability of an observation to date is less than 20 percent in contrast to past predictions. In 15 years we expect this figure to be near 60 percent. We conclude that the null result to date cannot be taken as evidence against the asymmetric kick hypothesis for the origin of pulsar velocities. We develop our model and apply it to binary pulsars in general. We conclude that the likelihood of observing geodetic precession in the near future is low.

A complete version of this paper is soon to be submitted to a scientific journal.

The current status of the theory of neutron star interiors is reviewed. The various phases of matter that might exist are discussed and their relation to other areas of astrophysics briefly noted. Observational distinction between the models is not simply obtained; analysis of pulsar post-glitch relation, of neutron star precession and neutron star cooling are promising in this regard.

To sort out the whole sample of pulsars with measured P and P into two types has much something to do with the origin and evolution of neutron stars. Under the configuration of two types of pulsars with different spindown mechanism, we have discussed a variety of their properties, including their radio emission mechanism, space velocities, interior structures and evolutionary modes. The fact that different type of pulsars does have quite different properties indicates that the processes to create neutron stars may have two distinct types, say, Type II supernova explosion and the collapse of accreting white dwarfs. The evolutionary mode for our Type I pulsars provides such a key link between binary pulsars and X-ray binary pulsars that we may propose a self-consistent scenario for binary pulsars, X-ray binary pulsars, fast pulsars as well as Type I pulsars.

Recent developments in the standard theory of neutron star cooling is critically reviewed. Emphasis is placed on the recent developments in the calculations of thermal conductivity and neutrino energy loss rates.

We study the possibility of the existence of quark matter during the early stage of hot neutron stars. According to Walecka (1978) and Shuryak (1980), we calculate the EOS of neutron matter and quark matter at different temperatures, T, in which we take the coupling constant αs to be 0.5 (Rafelski, 1982) and the bag constant B 1/4 to be 145, 170 and 190 Mev (Chin, 1978) due to a slight influence of αs and a great influence of B on our results. Supposing that neutron matter-quark matter phase transition is the first order phase transition (Baym and Chin, 1976), we obtain the phase transition pressures and densities at T = 3×1010 and 1012 K, respectively, from the relation between the pressure and the chemical potential. Then we try to determine the existence of quark matter thru the comparison of these densities with those of stable hot neutron stars.

The possibility existing crystal lattice in the interior of neutron stars is an interesting topic, Vela pulsar's glitches phenomenon is explained by means of this structure. There have been many articles in this respect in recent more than ten years. We are doing some work on the same topic.

Pulsar may be regarded as a discharge tube by electron-positron pair creation. On this viewpoint we carry out two numerical calculations. The obtained magnetic field is consistent with the flow. We find that pulsars emit their rotational energy through three modes simultaneously. The three modes are (1)relativistic acceleration and following gamma-ray emission in the closed current circuit in the magnetosphere, (2)wind of the electron-positron pair plasma, and (3)dipole radiation.

We took the magnetic susceptibility χ as a criterion in this study and supposed that the system of neutron matter has a ferromagnetic transition as 1/χ 0. The magnetic susceptibility of pure neutron matter at zero temperature was calculated by means of Owen's lowest order constraint variation method. The following results were obtained: if the interaction between neutron and neutron was the Reid soft-core potential, then no transition to ferromagnetic state was found to occur; if the interaction was HJ, IY potentials, the neutron matter would undergo a transition. These results indicate that the existence of ferromagnetic state depends on the form of potentials. If the interaction between particles is attractive, it will not profit the existence of ferromagnetic state, while the interaction between neutrons has a repulsive core, it will profit the existence of ferromagnetic state. We also calculated the equation of state and structure parameters of neutron stars. It showed that the energy of ferromagnetic state is lower than that of nonferromagnetic one and the ferromagnetic state is more stable. In other words, the ferromagnetic state may exist in neutron stars. We can readily find that ferromagnetic state has some influence on structure parameters of neutron stars, the magnitude of this effect depends on the form of potentials and the values of these structure parameters with ferromagnetism are within the allowed range. In this paper, the possibility existing the ferromagnetic state has been dsicussed. By a rough estimate, the magnetic field strength coming from the complete ferromagnetic state is about 1015 Gauss at ρ ∼ 1015 g/cm3. We assume that this is a possible origin of the strong magnetic fields in neutron stars. If there exists a ferromagnetic state in neutron stars, it will have a substantial influence on the gravitaional collapse theory, neutron superfluid and proton superconductivity.

Most of common curved magnetic fields with axial symmetry in astrophysics can be expressed in a local cylindrical coordinate system (R, φ, Z) as where HO, RO and N are real constants. It has been known that the non-zero curvature of the magnetic field lines can impose an additional pitch angle on the electrons moving in the field (1).

In strong magnetic field near pulsar's surface, the quantum effect for electrons is quite complicated. The classical approximation may lose resonance feature, which gives much smaller cross-section.

In this paper, we performed numerical integrations to get the total cross-section and the power spectrum of single electron. Thus considering the resonance, the inverse Compton scattering could be an efficient mechanism in strong magnetic fields. We have carefully calculated the power spectrum of single electron travelling through the isotropic thermal fields.

Neutron stars, like the earth, are rotating fluid-filled ellipsoids. Poincaré (Bull. Astron. 27, 321, 1910), Hough (Phil. Trans. R. Soc. A186, 469, 1895) and others have discussed the nutations of such objects through a simple model, which treats the crust as rigid and the core as an ideal fluid of uniform density and vorticity. The core and crust are coupled by inertial coupling: the forces which constrain the fluid to its cavity within the crust can produce a net torque, since the cavity is ellipsoidal. Additional torques, and the effects of the elasticity in the crust and density stratification in the core, may be accomodated in such models as well (Sasao et al., Proc. IAU Symposium 78, p. 165, 1980, and references therein).

We have calculated cooling models of young neutron stars.3 The theoretical cooling curves for several models are compared with the Einstein X-ray observations of young supernova remnants (Figure 1).

For years the theoretical models of neutron star formation and evolution had remained largely unconstrained by observation. Following the Einstein X-ray Observatory surveys of supernova remnants and pulsars, however, strict temperature limits were placed on many putative neutron stars. The Einstein search for additional objects in the class of supernova remnants with embedded pulsars has increased the number of such objects by two. For the four objects in this class, the surface temperature limits (see Table 1) provide meaningful logically sound constraints on the neutron star models. For the future, however, still better X-ray observations are needed, both to increase the number of objects available for study and to refine the spatial and spectral capabilities of the X-ray measurements.

The radiopulsar PSR1055-52 has been observed now by the Exosat observatory for about 105 sec, thus increasing the previously published data base (Brinkmann et al. 1985) by a factor of two. The pulsar was seen in the low energy telescope (0.04–2 keV) with the thin Lexan and Al/Par filters, but not in the Boron filter or with the ME experiment.

The failure of Einstein X-ray observations to detect central neutron stars in most young supernova remnants (Helfand and Becker 1984) has provided interesting constraints on cooling theories (cf. review by Tsuruta 1985). The comparison of the measured fluxes with the predicted effective temperatures is sensitive to the nature of the emitted spectrum, commonly assumed to be blackbody. The presence of a substantial absorbing atmosphere can, however, produce significant departures. We have calculated model atmospheres for unmagnetized neutron stars with effective temperatures 105K ≦ Teff ≦ 106.5K using Los Alamos opacities and equations of state (Romani 1986). We consider a range of surface compositions, since the accretion of ∼10−19M⊙ will cover the surface to the X-ray photosphere and subsequent settling in the strong gravitational field can severely deplete the heavy species. In a low Z atmosphere (eg. He) the measured X-ray flux will substantially exceed the blackbody value–the Einstein limits on Teff are correspondingly lowered (eg. by ∼1.6 for SN1006 with a helium surface). For high Z atmospheres, the flux is close to the black body value, but prominent absorption edges are present. Recent calculations of the electron heat transport in magnetized neutron star envelopes (Hernquist 1984, 1985) have shown that, contrary to earlier estimates, magnetic fields will have a small effect on the heat flux (≳ 3 for parallel field geometries and ∼1 for tangled fields). Extension of the atmosphere computations to the magnetic case is important for comparison with X-ray observations of known pulsars.

From KNK metric, we have shown that there may exist some kind of celestial bodies which can not collapse to black holes provided that the proportion of the content of the magnetic monopoles to the nuclei ξ = Nm/NB exceeds a critical value ξc (l-a2/Rg2), in which ξc =√G mB/gm ∼ 4.4 ×1021, a = J/Mc, Rg =GM/c2.

Based on Zakharov's equations, Karpman et al. claimed that there were solitons in the magnetosphere. According to the model proposed by Goldreich and Julin, there is a strong induced electric field in the magnetosphere. It seems that we should include the nonlinear effects of the electric field on the polarization of hydrogen atoms if there really are some hydrogen atoms spreading in the magnetosphere of the pulsar. Assuming the magnetosphere is symetric, therefore the electric polarization of hydrogen atoms is of the form P=χ(1)E +χχE3. We treat χ(1) and χ(2) as scalars because most hydrogen atoms in the universe are in the ground state and χ(3) is much smaller than χ(1).