Observations of gamma rays around 1012 eV (= 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.

An X-ray jet-like outflow, beginning at the Vela pulsar and extending about seven parsecs along the pulsar spin axis direction has recently been discovered (Markwardt & Ögelman 1995). We present data obtained by the X-ray ASCA satellite which confirms the enhanced X-ray emission at the jet head and discuss the allowable spectral models. The jet parameters are updated according to the combined ROSAT and ASCA results.

PSR 1509-58 is one of the youngest and most powerful pulsars known and is visible not only in soft X-rays, but in gamma-rays. Observations of its supernova remnant (MSH 15-52) offer a rare chance to study such a young pulsar and to explore its surroundings, which in X-rays include the pulsar’s 10×6 arcmin X-ray synchrotron nebula and the peculiar, filamentary optical nebula, RCW 89, that sits on the limb of MSH 15-52 (Seward & Harnden 1982, Seward et al. 1983). This paper will concentrate on the morphology of the synchrotron nebula.

Navarro et al. (1995) have discovered a 2.3 ms radio pulsar in a 2.0 day orbit around a low-mass companion. An interesting feature of this pulsar, PSR J0218+4232, is that radio emission is discovered throughout the pulse period; this is taken by Navarro et al. as an indication that the pulsar magnetic field is almost aligned with the rotation axis, and may also be related to the rather high radio luminosity of this pulsar, L400MHZ > 2700 mJy kpc2. The dispersion measure DM = 61.25pc cm−3 indicates a minimum distance of 5.7 kpc, according to the model for the free electron distribution in the Galaxy by Taylor and Cordes (1993).

We investigate the spectral attenuation due to one-photon pair production and photon splitting in neutron star magnetospheres. The calculations are performed in a Schwarzschild metric, thereby including redshift and field enhancement effects associated with curved spacetime. We find that pair production and splitting totally inhibit emission above around 10-30 MeV in PSR1509-58, whose surface field is inferred to be as high as 3 × 1013 Gauss. Model pulsar spectra of splitting cascades for high field cases, where splitting is important, are consistent with the very low cutoff energy in PSR1509-58 for a wide range of polar cap sizes.

We have developed a method for quantifying the flux variabilities of high energy gamma ray sources. We have applied this method to 128 sources listed in the second catalog of sources detected with the Energetic Gamma Ray Experiment Telescope (EGRET) (Thompson et. al. 1995). These sources include the Large Magellanic Cloud, 5 pulsars, 41 active galactic nuclei (AGN), and 81 sources not yet identified with known objects.

Our data include photon maps (E > 100 MeV) from 134 EGRET viewing periods spanning a roughly 3 year period. Each source was observed in 3-20 viewing periods ranging from a few days to 3 weeks in length. For each observation, a source flux was calculated using the method of maximum likelihood (Mattox et al. 1996) which simultaneously estimates the strength of the Galactic and isotropic diffuse emission, and that of a point source distributed as the EGRET point spread function.

We consider a close binary system with separation ≃ 0.2 R⊙ which consists of a (C+O) star of mass ≃ 4 M⊙ and a neutron star as a progenitor of soft gamma-ray repeater (SGR) and a high velocity pulsar. After the event of the supernova explosion, both new and old neutron stars have high relative velocity of ≃ 1000km s−1 to the center of mass of the ejecta. SGR activities can be induced by the episodic accretion of the supernova ejecta onto the old neutron star or the strange high rotating pulsar of the new neutron star. Future observations with fine positional resolution can clarify the position ambiguity between the gamma ray and X-ray sources.

We propose magnetic cannon ball mechanism in which the collapse of a magnetosphere onto a black hole can generate strong outward Poynting flux which can drive a baryon-free fireball. This process can occur at the final collapsing phase of a neutron star with strong magnetic field. The magnetic cannon ball can drive a relativistic outflow without the rotation of the central object. This baryon-free process can explain gamma-ray bursts as the final phase of dead pulsars.

The Collaboration of Australia and Nippon for a GAmma Ray Observatory in the Outback operates two large telescopes at Woomera (South Australia), which detect the Čerenkov light images produced in the atmosphere by electronpositron cascades initiated by very high energy (~1 TeV or 1012 eV) gamma rays. These gamma rays arise from a different mechanism than at EGRET energies: inverse Compton (IC) emission from relativistic electrons.

The spoke-like images are recorded by a multi-pixel camera which facilitates the rejection of the large numbers of oblique and ragged cosmic ray images. A field of view ~3.5° is required. The Australian team operates a triple 4 m diameter mirror telescope, BIGRAT, with a 37 photomultiplier tube camera and energy threshold 600 GeV. The Japanese operate a single, highly accurate 3.8 m diameter f/1 telescope and high resolution 256 photomultipler tube camera. In 1998 a new 7 m telescope is planned for Woomera with a design threshold ~;200GeV.

Results from the X-ray observations of pulsars with ASCA are presented. The surroundings of pulsars are investigated in detail taking advantage of ASCA’s unique capabilities; high spectral resolution and a high throughput over a wide energy range from 0.4 keV to 10 keV. The spectral characteristics of the nebulae of PSR B1509—58 and the Vela pulsar are spectroscopically investigated. A jet-like feature is found from PSR B1509—58. We detected diffuse emission sources in the vicinity of many pulsars. The high probability of finding such diffuse sources for many pulsars suggests that they exist universally for all the active pulsars, and that they are powered by the pulsars. SNR Kes 32 was imaged in X-ray for the first time. Its X-ray properties can be used to examine its association with the nearby pulsar PSR B1610—50.

We review proposed pulsar/supernova remnant associations, summarize recent highlights, including searches for young pulsars, searches for remnants, studies of previously proposed associations, and attempts at pulsar/remnant association syntheses. We argue that most proposed associations require additional investigation before they can be considered secure. Existing evidence from secure associations implies pulsars are born with large magnetic fields and short periods, but do not necessarily have particularly large radio luminosities. We argue that the evidence for large space velocities from associations is ambiguous.

We have performed Monte Carlo simulations of the Galactic supernova (SN), supernova remnant (SNR) and pulsar (PSR) populations, and find that even if every SN forms a fast-spinning pulsar, the number of shell type remnants which are expected to have an associated pulsar is even less than observed. We conclude that most shell SNRs will not have a detectable pulsar associated with them, and that many claimed associations are merely geometric projection.

The possibility of Langmuir wave generation in electronpositron plasma is considered. As a result of induced scattering, these waves find themselves in the superluminal region. Thereby such waves can transfer energy to the Crab Nebula essentially without loss, where the remaining plasma creates condition of collapse of Langmuir waves. As a result, the tail of the e± distribution function stretchs out to Lorentz factors of the order of γ± ≤ 109. Via synchrotron emission, particles of these energies can radiate X and γ - radiation.

I discuss pulsar wind nebulae for which ram pressure from the neutron star’s motion is a key element of the morphology. These PWN are tools for determining the pulsar distance, radial velocity component, and interaction of pulsar winds with surrounding media. The Guitar Nebula pulsar (B2224+65) also represents a ‘smoking gun’ for velocity kicks from asymmetric supernovae or other rocket effects. The detectability of wind nebulae from pulsars and from as-yet unknown neutron stars is discussed.

The shock excitation of pulsar powered nebulae (plerions) is discussed, based on recent theoretical work on the structure of relativistic, collisionless magnetosonic shock waves. This theory is used to outline a model in which the γ−2 injection spectrum of the Crab Nebula is satisfactorily accounted for. The same theory suggests a model of the “wisp” features in the Crab Nebula which accounts for these time variable features in the surface bightness as compressions associated with the magnetic overshoots within the shock structure. It is pointed out that this theory suggests observable variability in the high energy gamma rays from the Crab Nebula (ε > 50 MeV).

A gedanken experiment presented here provides basic understanding of how the pulsar magnetosphere operates. We discuss current issues about the electric-field acceleration along magnetic field lines and subsequent pair creation, and also about the pulsar wind problem. It is stressed that any local model, such as the inner gap model, the outer gap model and the pulsar wind model, must have free parameters to link it to other part of the magnetosphere.

Muslimov & Tsygan (1986, 1990, 1991, 1992) have shown how the dragging of inertial frames modifies the Goldreich-Julian charge density. The consequences are noted for different models of the electron outflow near the neutron star’s surface.

The structure and energetics of a rotation-modulated pulsar wind are examined. It is shown that the displacement current in the wind asymptotically dominates the conduction current, creating an outer radiation zone whose inner boundary lies well inside the wind termination shock. A self-consistent nonlinear-plasma-wave model of the radiation zone predicts that the ratio of Poynting flux to kinetic-energy flux at the termination shock is small (~ 10−3 for the Crab), in agreement with independent observational estimates.

To explain the pulsar wind acceleration and the energy conversion from the electromagnetic energy to the plasma’s kinetic energy between the pulsar and the nebula’s shock, we study relativistic cold ideal MHD winds in non-radial magnetic field geometry and clarify the critical conditions of trans-fast MHD winds.

Using fundamental equations of physics we determine with a simple model a globally self-consistent state of a pulsar magnetosphere.