Browsing Faculty of Natural and Agricultural Sciences by Subject "gamma rays: observations"

Now showing items 1-7 of 7

    • Constraints on the multi-TeV particle population in the Coma galaxy cluster with HESS observations 

      Aharonian, F.; Büsching, I.; Davids, I.D.; De Jager, O.C.; Holleran, M.; Raubenheimer, B.C.; Venter, C.; H.E.S.S. Collaboration (EDP Sciences, 2009)
      Aims. Galaxy clusters are key targets in the search for ultra high energy particle accelerators. The Coma cluster represents one of the best candidates for such a search owing to its high mass, proximity, and the established ...

    • HESS observations and VLT spectroscopy of PG 1553+113 

      Aharonian, F.; Büshing, I.; De Jager, O.C.; Holleran, M.; Raubenheimer, B.C.; Venter, C.; H.E.S.S. Collaboration (EDP Sciences, 2008)
      Aims.The properties of the very high energy (VHE; GeV) γ-ray emission from the high-frequency peaked BL Lac PG 1553+113 are investigated. An attempt is made to measure the currently unknown redshift of this object. Methods.VHE ...

    • HESS observations of y-ray bursts in 2003-2007 

      Aharonian, F.; Büsching, I.; De Jager, O.C.; Holleran, M.; Raubenheimer, B.C.; Venter, C.; H.E.S.S. Collaboration (EDP Sciences, 2009)
      Aims. Very-high-energy (VHE; $\ga$100 GeV) $\gamma $-rays are expected from $\gamma $-ray bursts (GRBs) in some scenarios. Exploring this photon energy regime is necessary for understanding the energetics and properties ...

    • HESS upper limit on the very high energy γ-ray emission from the globular cluster 47 Tucanae 

      Aharonian, F.; Holleran, M.; Büsching, I.; Davids, I.D.; De Jager, O.C.; Raubenheimer, B.C.; Venter, C.; H.E.S.S. Collaboration (EDP Sciences, 2009)
      Observations of the globular cluster 47 Tucanae (NGC 104), which contains at least 23 ms pulsars, were performed with the HESS telescope system. The observations lead to an upper limit of F(E > 800 GeV) < 6.7 × 10−13 cm−2 ...

    • HESS upper limits for Kepler's supernova remnant 

      Büsching, I.; De Jager, O.C.; Holleran, M.; Raubenheimer, B.C.; Venter, C.; H.E.S.S. Collaboration (EDP sciences, 2008)
      Aims. Observations of Kepler's supernova remnant (G4.5+6.8) with the HESS telescope array in 2004 and 2005 with a total live time of 13 h are presented. Methods. Stereoscopic imaging of Cherenkov radiation from extensive ...

    • HESS very-high-energy gamma-ray sources without identified counterparts 

      Büsching, I.; De Jager, O.C.; Holleran, M.; Raubenheimer, B.C.; Venter, C.; H.E.S.S. Collaboration (EDP sciences, 2008)
      Context.The detection of gamma rays in the very-high-energy (VHE) energy range (100 GeV–100 TeV) provides a direct view of the parent population of ultra-relativistic particles found in astrophysical sources. For this ...

    • Simultaneous HESS and Chandra observations of Sagitarius A* during an X-ray flare 

      Aharonian, F.; Büsching, I.; De Jager, O.C.; Holleran, M.; Raubenheimer, B.C.; Venter, C.; H.E.S.S. Collaboration (EDP Sciences, 2008)
      The rapidly varying (~10 min timescale) non-thermal X-ray emission observed from Sgr A implies that particle acceleration is occuring close to the event horizon of the supermassive black hole. The TeV γ-ray source ...