Now showing items 1-20 of 25

    • Constraints on the gamma-ray emission from the cluster-scale AGN outburst in the hydra A galaxy cluster 

      Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Casanova, S.; Pekeur, Nicolette Whilna; Sheidaei, F.; Venter, Christo; Vorster, Michael Johannes; Büsching, Ingo (EDP Sciences, 2012)
      Context. In some galaxy clusters, powerful active galactic nuclei (AGN) have blown bubbles with cluster scale extent into the ambient medium. The main pressure support of these bubbles is not known to date, but cosmic rays ...
    • Discovery of gamma-ray emission from the extragalactic pulsar wind nebula N 157B with H.E.S.S 

      Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Pekeur, Nicolette Whilna; Sheidaei, F.; Tavernet, J. P.; Venter, Christo; Vorster, Michael Johannes; De Jager, Ocker Cornelis (2012)
      We present the significant detection of the first extragalactic pulsar wind nebula (PWN) detected in gamma rays, N 157B, located in the large Magellanic Cloud (LMC). Pulsars with high spin-down luminosity are found to power ...
    • Discovery of hard-spectrum y-ray emission from the BL Lacertae object 1ES0414+009 

      Abramowski, A.; Büsching, Ingo; De Jager, Ocker Cornelis; Sheidaei, F.; Venter, Christo; Vorster, Michael Johannes (EDP Science, 2012)
      Context. 1ES 0414 + 009 (z = 0.287) is a distant high-frequency-peaked BL Lac object, and has long been considered a likely emitter of very-high-energy (VHE, E > 100 GeV) γ-rays due to its high X-ray and radio flux. Aims. ...
    • Discovery of TeV y–ray emission from PKS 0447–439 and derivation of an upper limit on its redshift 

      Abramowski, A.; Acero, F.; Vorster, Michael Johannes; Venter, Christo; Kruger, Petrus Paulus (EDP Sciences, 2013)
      Very high-energy γ-ray emission from PKS 0447−439 was detected with the H.E.S.S. Cherenkov telescope array in December 2009. This blazar is one of the brightest extragalactic objects in the Fermi bright source list and has ...
    • Discovery of the source HESS J1356-645 associated with the young and energetic PSR J1357-6429 

      Venter, Christo; Vorster, Michael Johannes; Büsching, Ingo; De Jager, Ocker Cornelis (EDP Sciences, 2011)
      Context. Several newly discovered very-high-energy (VHE; E > 100 GeV) γ-ray sources in the Galaxy are thought to be associated with energetic pulsars. Among them, middle-aged (≳104 yr) systems exhibit large centre-filled ...
    • Discovery of very high energy γ-ray emission from the BL Lacertae object PKS 0301−243 with H.E.S.S. 

      Abramowski, A.; Acero, F.; Vorster, Michael Johannes; Venter, Christo; Kruger, Petrus Paulus (EDP Sciences, 2013)
      The active galactic nucleus PKS 0301−243 (z = 0.266) is a high-synchrotron-peaked BL Lac object that is detected at high energies (HE, 100 MeV < E < 100 GeV) by Fermi/LAT. This paper reports on the discovery of PKS 0301−243 ...
    • Discovery of VHE emission towards the carina arm region with the H.E.S.S. telescope array: HESS J1018-589 

      Abramowski, A.; Büsching, Ingo; Casanova, S.; De Jager, Ocker Cornelis; Pekeur, Nicolette Whilna; Sheidaei, F.; Venter, Christo; Vorster, Michael Johannes (EDP Science, 2012)
      The Carina arm region, containing the supernova remnant SNR G284.3–1.8, the high-energy (HE; E > 100 MeV) binary 1FGL J1018.6–5856 and the energetic pulsar PSR J1016–5857 and its nebula, has been observed with the H.E.S.S. ...
    • H.E.S.S. constraints on dark matter annihilations towards the sculptor and carina dwarf galaxies 

      Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A.G.; Anton, G.; Barnacka, A.; Barres de Almeida, U.; Bazer-Bachi, A.R.; Becherini, Y.; Becker, J.; Behera, B.; Bernlöhr, K.; Bochow, A.; Boisson, C.; Bolmont, J.; Bordas, P.; Borrel, V.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Büsching, Ingo; Carrigan, S.; Casanova, S.; Cerruti, M.; Chadwick, P.M.; Charbonnier, A.; Chaves, R.C.G.; Cheesebrough, A.; Chounet, L. M.; Clapson, A.C.; Coignet, G.; Conrad, J.; Dalton, M.; Daniel, M.K.; De Jager, Ocker Cornelis; De Los Reyes, R.; De Naurois, M.; De Oña Wilhelmi, E.; Degrange, B.; Deil, C.; Dickinson, H.J.; Djannati-Ataï, A.; Domainko, W.; Drury, L.O'C.; Dubois, F.; Dubus, G.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Espigat, P.; Fallon, L.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M.V.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gallant, Y.A.; Gast, H.; Gérard, L.; Gerbig, D.; Giebels, B.; Glicenstein, J.F.; Glück, B.; Goret, P.; Göring, D.; Hague, J.D.; Hampf, D.; Hauser, M.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hoffmann, A.; Hofmann, W.; Hofverberg, P.; Horns, D.; Jacholkowska, A.; Jahn, C.; Jamrozy, M.; Jung, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Keogh, D.; Kerschhaggl, M.; Khangulyan, D.; Khélifi, B.; Klochkov, D.; Kluzniak, W.; Kneiske, T.; Komin, Nu; Kosack, K.; Kossakowski, R.; Laffon, H.; Lamanna, G.; Lennarz, D.; Lohse, T.; Lopatin, A.; Lu, C.C.; Marandon, V.; Marcowith, A.; Masbou, J.; Maurin, D.; Maxted, N.; Mccomb, T.J L.; Medina, M.C.; Méhault, J.; Moderski, R.; Moulin, E.; Naumann, C.L.; Naumann-Godo, M.; Nedbal, D.; Nekrassov, D.; Nguyen, N.; Nicholas, B.; Niemiec, J.; Nolan, S.J.; Ohm, S.; Olive, J.F.; Opitz, B.; Ostrowski, M.; Panter, M.; Paz Arribas, M.; Pedaletti, G.; Pelletier, G.; Petrucci, P.O.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raue, M.; Rayner, S.M.; Reimer, A.; Reimer, O.; Renaud, M.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C.B.; Ruppel, J.; Ryde, F.; Sahakian, V.; Santangelo, A.; Schlickeiser, R.; Schöck, F.M.; Schönwald, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Shalchi, A.; Sikora, M.; Skilton, J.L.; Sol, H.; Spengler, G.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Sushch, I.; Szostek, A.; Tavernet, J.P.; Terrier, R.; Tibolla, O.; Tluczykont, M.; Valerius, K.; Van Eldik, C.; Vasileiadis, G.; Venter, Christo; Vialle, J.P.; Viana, A.; Vincent, P.; Vivier, M.; Völk, H J.; Volpe, F.; Vorobiov, S.; Vorster, Michael Johannes; Wagner, S.J.; Ward, M. (Elsevier Science, 2011)
      The Sculptor and Carina dwarf spheroidal galaxies were observed with the H.E.S.S. Cherenkov telescope array between January 2008 and December 2009. The data sets consist of a total of 11.8 h and 14.8 h of high quality data, ...
    • H.E.S.S. discovery of VHE y–rays from the quasar PKS 1510–089 

      Abramowski, A.; Acero, F.; Vorster, Michael Johannes; Venter, Christo; Kruger, Petrus Paulus (EDP Sciences, 2013)
      The quasar PKS 1510−089 (z = 0.361) was observed with the H.E.S.S. array of imaging atmospheric Cherenkov telescopes during high states in the optical and GeV bands, to search for very high energy (VHE, defined as E ≥ 0.1 ...
    • H.E.S.S. observations of the binary system PSR B1259–63/LS 2883 around the 2010/2011 periastron passage 

      Abramowski, A.; Acero, F.; Vorster, Michael Johannes; Venter, Christo; Kruger, Petrus Paulus (EDP Sciences, 2013)
      Aims. We present very high energy (VHE; E > 100 GeV) data from the -ray binary system PSR B1259-63/LS 2883 taken around its periastron passage on 15th of December 2010 with the High Energy Stereoscopic System (H.E.S.S.) ...
    • H.E.S.S. observations of the globular clusters NGC 6388 and M15 and search for a dark matter signal 

      Venter, Christo; Vorster, Michael Johannes; Büsching, Ingo; De Jager, Ocker Cornelis (IOP Publishing, 2011)
      Observations of the globular clusters (GCs) NGC 6388 and M15 were carried out by the High Energy Stereoscopic System array of Cherenkov telescopes for a live time of 27.2 and 15.2 hr, respectively. No gamma-ray signal is ...
    • HESS J1943+213: a candidate extreme BL Lacertae object 

      Venter, Christo; Vorster, Michael Johannes; Büsching, Ingo; De Jager, Ocker Cornelis (EDP Sciences, 2011)
      We report on a newly detected point-like source, HESS J1943+213 located in the Galactic plane. This source coincides with an unidentified hard X-ray source IGR J19443+2117, which was proposed to have radio and infrared ...
    • Identification of HESS J1303-631 as a pulsar wind nebula through y-ray, x-ray, and radio observations 

      Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Balzer, A.; Casanova, S.; Pekeur, Nicolette Whilna; Sheidaei, F.; Venter, Christo; Vorster, Michael Johannes; Büsching, Ingo (EDP Science, 2012)
      Aims. The previously unidentified very high-energy (VHE; E > 100 GeV) γ-ray source HESS J1303−631, discovered in 2004, is re-examined including new data from the H.E.S.S. Cherenkov telescope array in order to identify this ...
    • Measurement of the extragalactic background light imprint on the spectra of the brightest blazars observed with H.E.S.S. 

      Abramowski, A.; Acero, F.; Vorster, Michael Johannes; Venter, Christo; Kruger, Petrus Paulus (EDP Sciences, 2013)
      The extragalactic background light (EBL) is the diffuse radiation with the second highest energy density in the Universe after the cosmic microwave background. The aim of this study is the measurement of the imprint of the ...
    • Modelling the evolution of pulsar wind nebulae 

      Vorster, Michael Johannes (2014)
      This study focusses on modelling important aspects of the evolution of pulsar wind nebulae using two different approaches. The first uses a hydrodynamic model to simulate the morphological evolution of a spherically-symmetric ...
    • A new SNR with TeV shell-type morphology: HESS J1731-347 

      Venter, Christo; Vorster, Michael Johannes; Büsching, Ingo; De Jager, Ocker Cornelis (EDP Sciences, 2011)
      Aims. The recent discovery of the radio shell-type supernova remnant (SNR), G353.6-0.7, in spatial coincidence with the unidentified TeV source HESS J1731−347 has motivated further observations of the source with the High ...
    • Probing the extent of the non-thermal emission from the Vela X region at TeV energies with H.E.S.S. 

      Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Balzer, A.; Pekeur, Nicolette Whilna; Sheidaei, F.; Venter, Christo; Vorster, Michael Johannes; Krüger, Petrus Paulus (EDP Science, 2012)
      Context. Vela X is a region of extended radio emission in the western part of the Vela constellation: one of the nearest pulsar wind nebulae, and associated with the energetic Vela pulsar (PSR B0833-45). Extended ...
    • Search for a dark matter annihilation signal from the galactic center halo with H.E.S.S. 

      Busching, Ingo; Venter, Christo; Vorster, Michael Johannes; Abramowski, A.; De Jager, Ocker Cornelis (American Physical Society (APS), 2011)
      A search for a very-high-energy (VHE; ≥100  GeV) γ-ray signal from self-annihilating particle dark matter (DM) is performed towards a region of projected distance r∼45–150  pc from the Galactic center. The background-subtracted ...
    • Search for dark matter annihilation signals from the fornax galaxy cluster with HESS 

      Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Venter, Christo; Vorster, Michael Johannes; Büsching, Ingo; De Jager, Ocker Cornelis (IOP publishers, 2012)
      The Fornax galaxy cluster was observed with the High Energy Stereoscopic System for a total live time of 14.5 hr, searching for very high energy (VHE; E > 100GeV) γ -rays from dark matter (DM) annihilation. No significant ...
    • Search for Lorentz invariance breaking with a likelihood fit of the PKS 2155-304 flare data taken on MJD 53944 

      Venter, Christo; Vorster, Michael Johannes; Büsching, Ingo; De Jager, Ocker Cornelis (Elsevier Science, 2011)
      Several models of Quantum Gravity predict Lorentz Symmetry breaking at energy scales approaching the Planck scale (∼1019 GeV). With present photon data from the observations of distant astrophysical sources, it is possible ...