Related papers: TeV Gamma-Ray Absorption and the Intergalactic Inf…
The energy spectrum of the Blazar type galaxy Markarian 501 (Mrk 501) as measured by the High-Energy-Gamma-Ray Astronomy (HEGRA) air Cerenkov telescopes extends beyond 16 TeV and constitutes the most energetic photons observed from an…
Regenerated high-energy emissions from gamma-ray bursts (GRBs) are studied in detail. If the intrinsic primary spectrum extends to the TeV range, these very high-energy photons are absorbed by the cosmic infrared background (CIB). Created…
The intensity of the extragalactic background (EBL), the accumulated optical and infrared emissions since the first stars, is the subject of a decades-long tension in the optical band. These photons form a target field that attenuates the…
Data taken with the HEGRA system of imaging atmospheric Cherenkov telescopes during the 1997 flares of Mkn 501 are reanalyzed using an algorithm providing improved energy resolution. A resolution of 10% to 12% is obtained by accounting for…
We outline a new method for estimating the cosmic infrared background using the spatial and spectral correlation properties of infrared maps. The cosmic infrared background from galaxies should have a minimum fluctuation of the order of…
Ultrahigh energy protons and nuclei from extragalactic cosmic ray sources initiate intergalactic electromagnetic cascades, resulting in observable fluxes of $\gamma$-rays in the GeV-TeV energy domain. The total spectrum of such cascade…
The Milagrito collaboration recently reported evidence for emission of very high energy gamma-rays in the TeV range from one of the BATSE GRBs, GRB 970417a. Here I discuss possible interpretations of this result. Taking into account the…
We report a measurement of intergalactic magnetic fields using combined data from Atmospheric Cherenkov Telescopes and Fermi Gamma-Ray Space Telescope, based on the spectral data alone. If blazars are assumed to produce both gamma rays and…
Gamma-ray emission from a narrow band at the Galactic equator has previously been detected up to 30 GeV. We report evidence for a TeV gamma-ray signal from the Galactic plane by Milagro, a large field of view water Cherenkov detector for…
The Intergalactic Magnetic Field (IGMF), permeating cosmic voids, is thought to be a relic of primordial magnetic fields generated in the early Universe and that gave rise to all astrophysical magnetic fields. While it has escaped direct…
A review of very high energy gamma-ray astronomy is presented. Particular attention is paid to the atmospheric Cherenkov imaging technique whose employment has resulted in detections of both galactic and extra-galactic objects at energies…
We spectrally fit the GeV gamma-ray flares recently-observed in the Crab Nebula by considering a small blob Lorentz-boosted towards us. We point out that the corresponding inverse-Compton flare at TeV--PeV region is more enhanced than…
The hunt for cosmic TeV particle accelerators is prospering through Imaging Atmospheric Cerenkov Telescopes. We face challenges such as low light levels and MHz trigger rates, and the need to distinguish between particle air showers…
Recent observations with the low threshold Cherenkov telescopes proved that sub-TeV gamma-rays are able to arrive from active galaxies at relatively large distances in spite of expected severe absorption in the extragalactic background…
Inverse-Compton cascades initiated by energetic gamma rays (E>100 GeV) enhance the GeV emission from bright, extragalactic TeV sources. The absence of this emission from bright TeV blazars has been used to constrain the intergalactic…
Intergalactic space is believed to contain non-zero magnetic fields (the Intergalactic Magnetic Field: IGMF) which at scales of Mpc would have intensities below $10^{-9}$ G. Very high energy (VHE $>$100 GeV) gamma rays coming from blazars…
Astrophysical sources outside the Milky Way, such as active galactic nuclei and star-forming galaxies, leave their imprint on the gamma-ray sky as nearly isotropic emission referred to as the Extragalactic Gamma-Ray Background (EGB). While…
A new method is described that permits quickly and easily, a 2-dimensional search for TeV gamma-ray sources over large fields of view ~6deg with instruments utilising the imaging atmospheric Cerenkov technique. It employs as a background…
The differential spectrum of TeV gamma rays between 1.5 TeV and 20 TeV from the north-east rim of SN1006 was obtained from the data observed in 1996 and 1997 using the 3.8m CANGAROO \v{C}erenkov telescope. This spectrum matches the model…
The window of TeV Gamma-Ray Astrophysics was opened less than two decades ago, when the Crab Nebula was detected for the first time. After several years of development, the technique used by imaging atmospheric Cherenkov telescopes like…