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Najdeno v: ključnih besedah
Ključne besede: Cherenkov Telescope Array, Gamma-Ray Bursts, very-high energy (VHE) gamma-ray emission, observational strategy optimization
Objavljeno: 11.03.2016; Ogledov: 2146; Prenosov: 143
Polno besedilo (133,05 KB)

Opis: Gamma Ray Bursts (GRBs) are the most energetic explosions in the universe, and they have been proposed as the most promising candidate sources of ultra-high energy cosmic rays (UHECRs). As a result of interactions of UHECR within the host environment and during their propagation towards Earth, high energy neutrinos and photons are also expected from both prompt and afterglow emission. In this talk, I will review the standard theory of particle acceleration and production in a GRB fireball, and multi-wavelength and multi-messeger observations of GRB emission. I will present the prediction of PeV — EeV neutrino production and evidence of GeV gamma ray radiation, and the expected detection in IceCube, Pierre Auger Observatory and CTA (the next generation of Imaging Atmospheric Cherenkov Telescopes). The investigation of high-energy particles will provide insight into the nature and complicated mechanisms of GRBs.
Najdeno v: ključnih besedah
Ključne besede: Gamma-Ray Bursts, high-energy emission, blastwave afterglow
Objavljeno: 06.12.2016; Ogledov: 1950; Prenosov: 0
Polno besedilo (20,49 MB)

Najdeno v: ključnih besedah
Ključne besede: astronomy, gamma ray bursts, polarisation
Objavljeno: 17.08.2017; Ogledov: 1310; Prenosov: 0
Polno besedilo (1,65 MB)

Opis: Bursts of gamma ray showers have been observed in coincidence with downward propagating negative leaders in lightning flashes by the Telescope Array Surface Detector (TASD). The TASD is a 700‐km^2 cosmic ray observatory located in southwestern Utah, USA. In data collected between 2014 and 2016, correlated observations showing the structure and temporal development of three shower‐producing flashes were obtained with a 3‐D lightning mapping array, and electric field change measurements were obtained for an additional seven flashes, in both cases colocated with the TASD. National Lightning Detection Network information was also used throughout. The showers arrived in a sequence of 2–5 short‐duration (≤10 μs) bursts over time intervals of several hundred microseconds and originated at an altitude of ≃3–5 km above ground level during the first 1–2 ms of downward negative leader breakdown at the beginning of cloud‐to‐ground lightning flashes. The shower footprints, associated waveforms and the effect of atmospheric propagation indicate that the showers consist primarily of downward‐beamed gamma radiation. This has been supported by GEANT simulation studies, which indicate primary source fluxes of ≃10^12–10^14 photons for 16° half‐angle beams. We conclude that the showers are terrestrial gamma ray flashes, similar to those observed by satellites, but that the ground‐based observations are more representative of the temporal source activity and are also more sensitive than satellite observations, which detect only the most powerful terrestrial gamma ray flashes.
Najdeno v: ključnih besedah
Povzetek najdenega: ... Bursts of gamma ray showers have been observed...
Ključne besede: gamma rays, lightning, gamma ray bursts, surface detector
Objavljeno: 30.04.2020; Ogledov: 556; Prenosov: 0
Polno besedilo (1,14 MB)