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Aims. The BL Lac object RGB J0152+017 (z = 0.080) was predicted to be a very high-energy (VHE; > 100 GeV) γ-ray source, due to its high X-ray and radio fluxes. Our aim is to understand the radiative processes by investigating the observed emission and its production mechanism using the High Energy Stereoscopic System (H.E.S.S.) experiment. Methods. 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)
Rotation as a source of asymmetry in the double-peak lightcurves of the bright EGRET pulsars Abstract. We investigate the role of rotational effects in inducing asymmetry present above ∼ 5 GeV in the double-peak lightcurves of the bright EGRET pul-sars: Vela, Crab, and Geminga. According to Thompson (2001), the trailing peak dominates over the leading peak(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)
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)
The giant radio galaxy M 87 with its proximity (16 Mpc), famous jet, and very massive black hole ((3 − 6) × 10 9 M) provides a unique opportunity to investigate the origin of very high energy (VHE; E>100 GeV) γ-ray emission generated in relativistic outflows and the surroundings of super-massive black holes. M 87 has been established as a VHE γ-ray emitter(More)
With the successful launch of the Swift Gamma-ray Burst Explorer, a rich trove of early X-ray afterglow data has been collected by its on-board X-Ray Telescope (XRT). Some interesting features are emerging, including a distinct rapidly decaying component preceding the conventional afterglow component in many sources, a shallow decay component before the(More)