This paper presents the theoretical basis of the fireball/blast wave model, and some implications of recent results on GRB source models and cosmic-ray production from GRBs. BATSE observations of the prompt γ-ray luminous phase, and Beppo-SAX and long wavelength afterglow observations of GRBs are briefly summarized. Derivation of spectral and temporal indices of an adiabatic blast wave decelera...

X-ray emission can provide a crucial diagnostic of gamma-ray bursts (GRBs). We calculate the X-ray and gamma-ray spectra of impulsive acceleration episodes related to GRB pulses. We use the synchrotron shock model (SSM) as a basis of our calculations. We show that the current data on soft-to-hard emission ratios of GRB pulse emission are in agreement with the SSM. In particular, GRB pulse emiss...

he X-Ray/Gamma-Ray Spectrometer on the Near Earth Asteroid Rendezvous (NEAR) spacecraft will remotely sense X-ray and gamma-ray emissions from the surface of near-Earth asteroid 433 Eros and look for characteristic “signatures” in those emissions to determine its elemental composition. During the planned 10 months of orbits about Eros beginning in early 1999, data returned from the instrument w...

The afterglow emission has become the main stream of Gamma-Ray burst research since its discovery three years ago. With the distance-scale enigma solved, the study of the late-time GRB emission is now the most promising approach to disclose the origin of these explosions and their relationship with the environment of the host galaxy in the early phase of the Universe. In this contribution I wil...

Observational evidence of iron absorption and emission lines in X-ray spectra of Gamma-Ray Bursts is quite compelling. I will briefly review the results, summarize different models and describe the connection with massive progenitors in star-forming regions implied by these results. This link is also supported by measurements of the X-ray absorbing gas in several GRB’s, with column density cons...

there are two methods for identifying formation interface in oil wells: core analysis, which is a precise approach but costly and time consuming, and well logs analysis, which petrophysists perform, which is subjective and not completely reliable. in this paper, a novel coupled method was proposed to detect the formation interfaces using gr logs. second approximation level (a2) of gr log gained...

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The vast majority of the celestial gamma-ray sources detected so far have not yet been identified with secure counterparts at other wavelenghts. Here we report the preliminary evidence of a probable association between galaxy clusters and unidentified gamma-ray sources of high galactic latitude (|b| > 20 deg) in the Third EGRET catalog. All of the clusters which are most probably associated wit...

We present a study of the unidentified gamma-ray source 3EG J0542+2610. This source is spatially superposed to the supernova remnant G180.0-1.7, but its time variability makes unlikely a physical link. We have searched into the EGRET location error box for compact radio sources that could be the low energy counterpart of the gamma-ray source. Although 29 point-like radio sources were detected a...

It is widely believed that outflows of gamma-ray bursts are jetted. Some people also suggest that the jets may have structures like ǫ(θ) ∝ θ. We test the possibility of X-ray flashes coming from such jets in this paper. Both qualitative and quantitative analyses have shown that this model can reproduce most observational features for both X-ray flashes and gamma-ray bursts. Using common paramet...