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The detection of fast variations of the tera-electron volt (TeV) (10(12) eV) gamma-ray flux, on time scales of days, from the nearby radio galaxy M87 is reported. These variations are about 10 times as fast as those observed in any other wave band and imply a very compact emission region with a dimension similar to the Schwarzschild radius of the central(More)
Aims. We present deep H.E.S.S. observations of the supernova remnant (SNR) RX J1713.7−3946. Combining data of three years – from 2003 to 2005 – we obtain significantly increased statistics and energy coverage as compared to earlier 2003 & 2004 results. Methods. The data are analysed separately for the different years. Results. Very good agreement of the(More)
The accretion of matter onto a massive black hole is believed to feed the relativistic plasma jets found in many active galactic nuclei (AGN). Although some AGN accelerate particles to energies exceeding 10(12) electron volts and are bright sources of very-high-energy (VHE) gamma-ray emission, it is not yet known where the VHE emission originates. Here we(More)
In the past few decades, several models have predicted an energy dependence of the speed of light in the context of quantum gravity. For cosmological sources such as active galaxies, this minuscule effect can add up to measurable photon-energy dependent time lags. In this Letter a search for such time lags during the High Energy Stereoscopic System(More)
Aims. To investigate the very high energy (VHE: >100 GeV) γ-ray emission from the high-frequency peaked BLLac 1ES 0229+200. Methods. Observations of 1ES 0229+200 at energies above 580 GeV were performed with the High Energy Stereoscopic System (HESS) in 2005 and 2006. Results. 1ES 0229+200 is discovered by HESS to be an emitter of VHE photons. A signal is(More)
The very large collection area of ground-based gamma-ray telescopes gives them a substantial advantage over balloon or satellite based instruments in the detection of very-high-energy (>600 GeV) cosmic-ray electrons. Here we present the electron spectrum derived from data taken with the High Energy Stereoscopic System (H.E.S.S.) of imaging atmospheric(More)
Starburst galaxies exhibit in their central regions a highly increased rate of supernovae, the remnants of which are thought to accelerate energetic cosmic rays up to energies of approximately 10(15) electron volts. We report the detection of gamma rays--tracers of such cosmic rays--from the starburst galaxy NGC 253 using the High Energy Stereoscopic System(More)
Compared with electromagnetic ballasts, electronic ballasts have much shorter lifetime and are not recyclable. This prompts new concerns about their environmental impacts due to the accumulation of toxic and non-biodegradable waste components and materials. In this paper, the combined use of a central dimming system with low-loss electromagnetic ballasts is(More)
Aims. HESS J1745−303 is an extended, unidentified VHE (very high energy) gamma-ray source discovered using H.E.S.S. in the Galactic Plane Survey. Since no obvious counterpart has previously been found in longer-wavelength data, the processes that power the VHE emission are not well understood. Methods. Combining the latest VHE data with recent XMM-Newton(More)
Aims. We present the results of a search for pulsed very-high-energy (VHE) γ-ray emission from young pulsars using data taken with the H.E.S.S. imaging atmospheric Cherenkov telescope system. Methods. Data on eleven pulsars, selected according to their spin-down luminosity relative to distance, are searched for γ-ray signals with periodicity at the(More)