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N. Magnussen

Publications and source records attributed to N. Magnussen.

5 recordsLinked to original sources
arXiv1999

The Physics Potential of Ground-Based Gamma-Ray Astronomy below 50 GeV

Currently three ground-based Air Cherenkov detectors with energy thresholds below 50 GeV are being commissioned (CELESTE and STACEE) or under construction (MAGIC Telescope). Based on the expected performance of the MAGIC Telescope and with an emphasis on those physics questions which are unique to the energy domain below 50 GeV an overview of the scientific prospects of ground-based high energy Gamma-Ray Astronomy in terms of astrophysics, cosmology and particle physics questions is given.

astro-ph↗
arXiv1998

Search for gamma-ray bursts above 20 TeV with the HEGRA AIROBICC Cherenkov array

A search for gamma-ray bursts (GRBs) above 20 TeV within the field of view (1 sr) of the HEGRA AIROBICC Cherenkov array (29N, 18W, 2200 m a.s.l.) has been performed using data taken between March 1992 and March 1993. The search is based on an all-sky survey using four time scales, 10 seconds, 1 minute, 4 minutes and 1 hour. No evidence for TeV-emission has been found for the data sample. Flux upper limits are given. A special analysis has been performed for GRBs detected by BATSE and WATCH. Two partially and two fully contained GRBs in our field of view (FOV) were studied. For GRB 920925c which was fully contained in our FOV, the most significant excess has a probability of 7.7 10**-8 (corresponding to 5.4 sigmas) of being caused by a background fluctuation. Correcting this probability with the appropriate trial factor, yields a 99.7% confidence level for this excess to be related to the GRB (corresponding to 2.7 sigmas). This result is discussed within the framework of the WATCH detection.

astro-ph↗
arXiv1998

The MAGIC Telescope Project for Gamma Astronomy above 10 GeV

A project to construct a 17 m diameter imaging air Cherenkov telescope, called the MAGIC Telescope, is described. The aim of the project is to close the observation gap in the gamma-ray sky extending from 10 GeV as the highest energy measurable by space-borne experiments to 300 GeV, the lowest energy measurable by the current generation of ground-based Cherenkov telescopes. The MAGIC Telescope will incorporate several new features in order to reach the very low energy threshold. At the same time the new technology will yield an improvement in sensitivity in the energy region where current Cherenkov telescopes are measuring by about an order of magnitude.

astro-ph↗
arXiv1998

An Upper Limit on the Infrared Background Density from HEGRA data on Mkn501

The energy spectrum of Mkn501 in the TeV energy regime, as measured by the HEGRA (High Energy Gamma Ray Astronomy) Cerenkov telescopes during its low state in 1995/96 and during a fraction of the 1997 outburst in the TeV energy regime, is shown to place stringent upper limits on the still unknown infrared photon density in the energy region between 3 x 10**(-3) and 3 xt 10**(-1) eV. Assuming two different shapes for the unknown infrared photon spectrum in this energy range we calculate upper limits on the infrared photon density on the basis of the power-law fit obtained for the observed spectrum up to the maximum energy.

astro-ph↗