No abstract

We make a modification of our previous outer gap model of high-energy emission from millisecond pulsars (MSPs) by taking the effects of the magnetic inclination angles and magnetic geometry into account. In the revised version of our outer gap model, a strong multipole magnetic field exists near the stellar surface, and the X-rays are produced by the backflow current of the outer gap and consist of one power-law and two thermal components. These X-rays collide with high-energy photons inside the outer gap to sustain the outer gap, and then high-energy -rays are produced in the outer gap. The fractional size of the outer gap is a function of the radial distance to the neutron star and the magnetic inclination angle for a given millisecond pulsar. We have applied this model to account for the pulsed X-ray emission from the MSPs outside of and in the globular cluster 47 Tuc, and our results indicate that the relation between the pulsed component of X-ray luminosity (L for the MSPs in 47 Tuc. We also applied our model to predict the averaged high-energy -ray fluxes and to compare them with the sensitivity of AGILE and GLAST.

Young pulsars with ages less than 10 6 yr are powerful particle accelerators, which can accelerate protons to relativistic energies above the polar cap region if the magnetic moment is antiparallel to the spin axis. The interaction of those protons with the soft X-ray photons coming from the neutron star surface can produce high-energy muon neutrinos through photomeson production. Therefore, those pulsars are promising candidates as high-energy neutrino sources. We produce a sample of young pulsars in our Galaxy using a Monte Carlo method, determine whether they are potential neutrino pulsars, and calculate the total neutrino fluxes from those young pulsars using the Link & Burgio (LB) model. We obtain the upper limit of the diffuse neutrino flux from the young pulsars in the Galaxy, and compare it with predicted results from active galactic nuclei (AGNs) and gamma-ray bursts (GRBs).

Fermi-LAT has detected pulsed gamma-ray emissions with high confidences from more than 40 millisecond pulsars (MSPs). Here we study the phase-averaged gamma-ray properties of MSPs by using revised version of a self-consistent outer gap model. In this model, a strong multipole magnetic field near the stellar surface for a MSP is assumed and such a field will be close to the surface magnetic fields (∼ 10 11 −10 12 G) of young pulsars; the outer gap of a MSP is controlled by photon-photon pair production process, where the effects of magnetic inclination angle (α) and magnetic geometry have been taken into account, therefore the fractional size of the outer gap is a function of not only pulsar's period and magnetic field strength but also magnetic inclination angle and radial distance to the neutron star, the inner boundary of the outer gap can be estimated by the pair production process of the gamma-ray photons which are produced by the back-flowing particles through the null charge surface; inside the outer gap, a Gaussian distribution of the parallel electric field along the trans-field thickness is assumed, and the gamma-ray emission is represented by the emission from the average radial distance along the central field lines of the outer gap. Using this model, the phase-averaged gamma-ray spectra are calculated and compared with the observed spectra of 37 MSPs given by the second Fermi-LAT catalog of gamma-ray pulsars, our results show that the Fermi-LAT results can be well explained by this model. The thermal X-ray emission properties from MSPs are also investigated.