The exact location of the γ -ray emitting region in blazars is still controversial. In order to attack this problem we present first results of a cross-correlation analysis between radio (11 cm to 0.8mm wavelength, F-GAMMA programme) and γ -ray (0.1–300GeV) ∼3.5 yr light curves of 54 Fermi-bright blazars. We perform a source stacking analysis and estimate significances and chance correlations u...

Soft γ-ray repeaters are at determined distances and their positions are known accurately. If observed, afterglows from their soft γ-ray bursts will provide important clues to the study of the so called " classical γ-ray bursts ". On applying the popular fireball/blastwave model of classical γ-ray bursts to soft γ-ray repeaters, it is found that their X-ray and optical afterglows are detectable...

We have carried out a new study of the diffuse Galactic γ-ray continuum radiation using a cosmic-ray propagation model which includes nucleons, antiprotons, electrons, positrons, and synchrotron radiation. We show that models based on locally measured electron and nucleon spectra and synchrotron constraints are consistent with γ-ray measurements in the 30 MeV – 500 MeV range, but outside this r...

With the ASCA X-ray satellite, we perform spatial and spectral studies of the shell-type supernova remnant (SNR) γ Cygni that is associated with the brightest EGRET unidentified source 3EG J2020+4017. At energies below 3 keV the bulk of the X-ray flux from the remnant is well described by the emission of thermal plasma with characteristic temperature kTe ≃ 0.5–0.9 keV. In addition to this therm...

We report circumstantial evidence for the first detection of pulsed high-energy γ-ray emission from a millisecond pulsar, PSR J0218+4232, using data collected with the Energetic Gamma Ray Experiment (EGRET) on board the Compton Gamma Ray Observatory (CGRO). The EGRET source 3EG J0222+4253 is shown to be spatially consistent with PSR J0218+4232 for the energy range 100–300 MeV. Above 1 GeV the n...

A review of the possible relationship between γ-ray sources and supernova remnants (SNRs) is presented. Particular emphasis is given to the analysis of the observational status of the problem of cosmic ray acceleration at SNR shock fronts. All positional coincidences between SNRs and unidentified γ-ray sources listed in the Third EGRET Catalog at low Galactic latitudes are discussed on a case b...

The Perseus galaxy cluster was observed by the MAGIC Cherenkov telescope for a total effective time of 24.4 hours during November and December 2008. No significant γ-ray excess was detected. The resulting upper limits on the γ-ray emission above 100 GeV are 4.63 and 6.55 × 10−12cm−2 s−1 for spectral indices of −1.5 and −2.2, respectively. The obtained limits constrain the emission produced by c...

nano-sized γ-al2o3 was synthesized successfully by a simple method using al2(so4)3·18h2o as aluminium source and in the presence of polyethylene glycol (peg 2000). ftir spectroscopy, x-ray diffraction (xrd), scanning electron microscope (sem) and transmission electron microscope (tem) were used to characterize the structure and morphology of synthesized powder. the results showed that peg playe...

We have developed a model which aims to reproduce observational data of many kinds related to cosmic-ray origin and propagation: direct measurements of nuclei, antiprotons, electrons and positrons, γ-rays, and synchrotron radiation. Our main results include evaluation of diffusion/convection and reacceleration models, estimates of the halo size, calculations of the interstellar positron and ant...