Now showing items 1-20 of 33

    • The 2010 very high energy γ-ray flare and 10 years of multi-wavelength observations of M 87 

      Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Büsching, Ingo; De Jager, Ocker Cornelis; Sheidaei, F.; Vorster, M. (IOP publishing, 2012)
      The giant radio galaxy M 87 with its proximity (16 Mpc), famous jet, and very massive black hole ((3 – 6) × 109 M☉) provides a unique opportunity to investigate the origin of very high energy (VHE; E > 100 GeV) γ-ray ...
    • Constraints on axionlike particles with H.E.S.S. from the irregularity of the PKS 2155–304 energy spectrum 

      Abramowski, A.; Casanova, S.; Krüger, P.P.; Pekeur, N.W.; Sushch, I.; Venter, C.; Vorster, M. (American Physical Society, 2013)
      Axionlike particles (ALPs) are hypothetical light (sub-eV) bosons predicted in some extensions of the Standard Model of particle physics. In astrophysical environments comprising high-energy gamma rays and turbulent ...
    • 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 extended VHE Y-ray emission from the vicinity of the young massive stellar cluster Westerlund 1 

      Abramowski, A.; Büsching, Ingo; De Jager, Ocker Cornelis; Sheidaei, F.; Venter, Christo; Vorster, M. (EDP Science, 2012)
      Aims. Results obtained in very-high-energy (VHE; E≥100GeV) γ-ray observations performed with the H.E.S.S. telescope array are used to investigate particle acceleration processes in the vicinity of the young massive stellar ...
    • 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 hard spectrum VHE γ-ray source HESS J1641-463 

      Abramowski, A.; Böttcher, M.; Davids, I.D.; Ivascenko, A.; Krüger, P.P.; Pekeur, N.W.; Spanier, F.; Sushch, I.; Venter, C.; Vorster, M. (IOP Publishing, 2014)
      This Letter reports the discovery of a remarkably hard spectrum source, HESS J1641–463, by the High Energy Stereoscopic System (H.E.S.S.) in the very high energy (VHE) domain. HESS J1641–463 remained unnoticed by the usual ...
    • 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. ...
    • Discovery of VHE Y-ray emission and multi-wavelength observations of the BL Lacertae object 1rx J101015.9-311909*bject 1rx J101015.9–311909* 

      Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Cologna, G.; Hauser, M.; Kaufmann, S.; Mohamed, M.; Quirrenbach, A.; Schwemmer, S.; Lenain, J-P.; Wagner, S.J. (EDP Science, 2012)
      1RXS J101015.9 − 311909 is a galaxy located at a redshift of z = 0.14 hosting an active nucleus (called AGN) belonging to the class of bright BL Lac objects. Observations at high (HE, E > 100 MeV) and very high (VHE, E > ...
    • Flux upper limits for 47 AGN observed with H.E.S.S. in 2004-2011 

      Abramowski, A.; Casanova, S.; Davids, I.D.; Krüger, P.P.; Pekeur, N.W.; Sushch, I.; Venter, C.; Vorster, M. (EDP Sciences, 2014)
      Context. About 40% of the observation time of the High Energy Stereoscopic System (H.E.S.S.) is dedicated to studying active galactic nuclei (AGN), with the aim of increasing the sample of known extragalactic very-high-energy ...
    • 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.) ...
    • HESS and fermi-LAT discovery of γ-rays from the blazar 1ES 1312−423 

      Abramowski, A.; Casanova, S.; Krüger, P.P.; Pekeur, N.W.; Sushch, I.; Venter, C.; Vorster, M. (Oxford University Press, 2013)
      A deep observation campaign carried out by the High Energy Stereoscopic System (HESS) on Centaurus A enabled the discovery of γ-rays from the blazar 1ES 1312−423, 2° away from the radio galaxy. With a differential flux at ...
    • HESS J1640−465 – an exceptionally luminous TeV γ -ray supernova remnant 

      Abramowski, A.; Casanova, S.; Davids, I.D.; Krüger, P.P.; Pekeur, N.W.; Sushch, I.; Venter, C.; Vorster, M.; Böttcher, M. (Oxford University Press, 2014)
      The results of follow-up observations of the TeV γ-ray source HESS J1640−465 from 2004 to 2011 with the High Energy Stereoscopic System (HESS) are reported in this work. The spectrum is well described by an exponential ...
    • HESSJ1818–154, a new composite supernova remnant discovered in TeV gamma rays and X-rays 

      Abramowski, A.; Böttcher, M.; Casanova, S.; Davids, I.D.; Krüger, P.P.; Pekeur, N.W.; Sushch, I.; Venter, C.; Vorster, M. (EDP Sciences, 2014)
      Composite supernova remnants (SNRs) constitute a small subclass of the remnants of massive stellar explosions where non-thermal radiation is observed from both the expanding shell-like shock front and from a pulsar wind ...
    • 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 ...
    • Long-term monitoring of PKS2155-304 with ATOM and H.E.S.S.: investigation of optical/y-ray correlations in different spectral states 

      Abramowski, A.; Böttcher, M.; Davids, I.D.; Ivascenko, A.; Krüger, P.P.; Pekeur, N.W.; Spanier, F.; Sushch, I.; Venter, C.; Vorster, M. (EDP Sciences, 2014)
      In this paper we report on the analysis of all the available optical and very high-energy y-ray (>200 GeV) data for the BL Lac object PKS 2155-304, collected simultaneously with the ATOM and H.E.S.S. telescopes from ...