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  • 1. Abdalla, H.
    et al.
    Aharonian, F.
    Benkhali, F. Ait
    Anguner, E. O.
    Arakawa, M.
    Arcaro, C.
    Armand, C.
    Arrieta, M.
    Backes, M.
    Barnard, M.
    Becherini, Y.
    Tjus, J. Becker
    Berge, D.
    Bernloehr, K.
    Blackwell, R.
    Bottcher, M.
    Boisson, C.
    Bolmont, J.
    Bonnefoy, S.
    Bordas, P.
    Bregeon, J.
    Brun, F.
    Brun, P.
    Bryan, M.
    Buchele, M.
    Bulik, T.
    Bylund, T.
    Capasso, M.
    Caroff, S.
    Carosi, A.
    Casanova, S.
    Cerruti, M.
    Chakraborty, N.
    Chand, T.
    Chandra, S.
    Chaves, R. C. G.
    Chen, A.
    Colafrancesco, S.
    Condon, B.
    Davids, I. D.
    Deil, C.
    Devin, J.
    deWilt, P.
    Dirson, L.
    Djannati-Atai, A.
    Dmytriiev, A.
    Donath, A.
    Doroshenko, V.
    Drury, L. O'C.
    Dyks, J.
    Egberts, K.
    Emery, G.
    Ernenwein, J. -P.
    Eschbach, S.
    Fegan, S.
    Fiasson, A.
    Fontaine, G.
    Funk, S.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gate, F.
    Giavitto, G.
    Glawion, D.
    Glicenstein, J. F.
    Gottschall, D.
    Grondin, M. -H.
    Hahn, J.
    Haupt, M.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hofmann, W.
    Hoischen, C.
    Holch, T. L.
    Holler, M.
    Horns, D.
    Huber, D.
    Iwasaki, H.
    Jacholkowska, A.
    Jamrozy, M.
    Jankowsky, D.
    Jankowsky, F.
    Jouvin, L.
    Jung-Richardt, I.
    Kastendieck, M. A.
    Katarzynski, K.
    Katsuragawa, M.
    Katz, U.
    Khangulyan, D.
    Khelifi, B.
    King, J.
    Klepser, S.
    Kluzniak, W.
    Komin, Nu.
    Kosack, K.
    Kraus, M.
    Lamanna, G.
    Lau, J.
    Lefaucheur, J.
    Lemiere, A.
    Lemoine-Goumard, M.
    Lenain, J. -P.
    Leser, E.
    Lohse, T.
    Lopez-Coto, R.
    Lorentz, M.
    Lypova, I.
    Malyshev, D.
    Marandon, V.
    Marcowith, A.
    Mariaud, C.
    Marti-Devesa, G.
    Marx, R.
    Maurin, G.
    Meintjes, P. J.
    Mitchell, A. M. W.
    Moderski, R.
    Mohamed, M.
    Mohrmann, L.
    Moore, C.
    Moulin, E.
    Murach, T.
    Nakashima, S.
    de Naurois, M.
    Ndiyavala, H.
    Niederwanger, F.
    Niemiec, J.
    Oakes, L.
    O'Brien, P.
    Odaka, H.
    Ohm, S.
    Ostrowski, M.
    Oya, I.
    Panter, M.
    Parsons, R. D.
    Perennes, C.
    Petrucci, P. -O.
    Peyaud, B.
    Piel, Q.
    Pita, S.
    Poireau, V.
    Noel, A. Priyana
    Prokhorov, D. A.
    Prokoph, H.
    Puehlhofer, G.
    Punch, M.
    Quirrenbach, A.
    Raab, S.
    Rauth, R.
    Reimer, A.
    Reimer, O.
    Renaud, M.
    Rieger, F.
    Rinchiuso, L.
    Romoli, C.
    Rowell, G.
    Rudak, B.
    Ruiz-Velasco, E.
    Sahakian, V.
    Saito, S.
    Sanchez, D. A.
    Santangelo, A.
    Sasaki, M.
    Schlickeiser, R.
    Schussler, F.
    Schulz, A.
    Schutte, H.
    Schwanke, U.
    Schwemmer, S.
    Seglar-Arroyo, M.
    Senniappan, M.
    Seyffert, A. S.
    Shafi, N.
    Shilon, I.
    Shiningayamwe, K.
    Simoni, R.
    Sinha, A.
    Sol, H.
    Specovius, A.
    Spir-Jacob, M.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Steppa, C.
    Takahashi, T.
    Tavernet, J. -P.
    Tavernier, T.
    Taylor, A. M.
    Terrier, R.
    Tiziani, D.
    Tluczykont, M.
    Trichard, C.
    Tsirou, M.
    Tsuji, N.
    Tuffs, R.
    Uchiyama, Y.
    van der Walt, D. J.
    van Eldik, C.
    van Rensburg, C.
    van Soelen, B.
    Vasileiadis, G.
    Veh, J.
    Venter, C.
    Vincent, P.
    Vink, J.
    Voisin, F.
    Voelk, H. J.
    Vuillaume, T.
    Wadiasingh, Z.
    Wagner, S. J.
    Wagner, Robert M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    White, R.
    Wierzcholska, A.
    Yang, R.
    Yoneda, H.
    Zaborov, D.
    Zacharias, M.
    Zanin, R.
    Zdziarski, A. A.
    Zech, A.
    Ziegler, A.
    Zorn, J.
    Zywucka, N.
    HESS observations of the flaring gravitationally lensed galaxy PKS 1830-2112019Ingår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 486, nr 3, s. 3886-3891Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PKS 1830-211 is a known macrolensed quasar located at a redshift of z = 2.5. Its highenergy gamma-ray emission has been detected with the Fermi-Large Area Telescope (LAT) instrument and evidence for lensing was obtained by several authors from its high-energy data. Observations of PKS 1830-211 were taken with the High Energy Stereoscopic System (H.E.S.S.) array of Imaging Atmospheric Cherenkov Telescopes in 2014 August, following a flare alert by the Fermi-LAT Collaboration. The H.E.S.S observations were aimed at detecting a gamma-ray flare delayed by 20-27 d from the alert flare, as expected from observations at other wavelengths. More than 12 h of good-quality data were taken with an analysis threshold of similar to 67 GeV. The significance of a potential signal is computed as a function of the date and the average significance over the whole period. Data are compared to simultaneous observations by Fermi-LAT. No photon excess or significant signal is detected. An upper limit on PKS 1830-211 flux above 67 GeV is computed and compared to the extrapolation of the Fermi-LAT flare spectrum.

  • 2. Abramowski, A.
    et al.
    Acero, F.
    Aharonian, F.
    Akhperjanian, A. G.
    Anton, G.
    Balenderan, S.
    Balzer, A.
    Barnacka, A.
    Becherini, Y.
    Becker, J.
    Bernloehr, K.
    Birsin, E.
    Biteau, J.
    Bochow, A.
    Boisson, C.
    Bolmont, J.
    Bordas, P.
    Brucker, J.
    Brun, F.
    Brun, P.
    Bulik, T.
    Carrigan, S.
    Casanova, S.
    Cerruti, M.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Cologna, G.
    Conrad, Jan M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Couturier, C.
    Dalton, M.
    Daniel, M. K.
    Davids, I. D.
    Degrange, B.
    Deil, C.
    Dickinson, Hugh J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O'C.
    Dubus, G.
    Dutson, K.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Eger, P.
    Espigat, P.
    Fallon, L.
    Farnier, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fegan, S.
    Feinstein, F.
    Fernandes, M. V.
    Fernandez, D.
    Fiasson, A.
    Fontaine, G.
    Foerster, A.
    Fuessling, M.
    Gajdus, M.
    Gallant, Y. A.
    Garrigoux, T.
    Gast, H.
    Gerard, L.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goering, D.
    Grondin, M. -H.
    Haeffner, S.
    Hague, J. D.
    Hahn, J.
    Hampf, D.
    Harris, J.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hillert, A.
    Hinton, J. A.
    Hofmann, W.
    Hofverberg, P.
    Holler, M.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jahn, C.
    Jamrozy, M.
    Jung, I.
    Kastendieck, M. A.
    Katarzynski, K.
    Katz, U.
    Kaufmann, S.
    Khelifi, B.
    Klochkov, D.
    Kluzniak, W.
    Kneiske, T.
    Komin, Nu.
    Kosack, K.
    Kossakowski, R.
    Krayzel, F.
    Laffon, H.
    Lamanna, G.
    Lenain, J. -P.
    Lennarz, D.
    Lohse, T.
    Lopatin, A.
    Lu, C. -C.
    Marandon, V.
    Marcowith, A.
    Masbou, J.
    Maurin, G.
    Maxted, N.
    Mayer, M.
    McComb, T. J. L.
    Medina, M. C.
    Mehault, J.
    Menzler, U.
    Moderski, R.
    Mohamed, M.
    Moulin, E.
    Naumann, C. L.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nguyen, N.
    Nicholas, B.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Wilhelmi, E. de Ona
    Opitz, B.
    Ostrowski, M.
    Oya, I.
    Panter, M.
    Arribas, M. Paz
    Pekeur, N. W.
    Pelletier, G.
    Perez, J.
    Petrucci, P. -O.
    Peyaud, B.
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Quirrenbach, A.
    Raue, M.
    Reimer, A.
    Reimer, O.
    Renaud, M.
    de los Reyes, R.
    Rieger, F.
    Ripken, Joachim
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Sahakian, V.
    Sanchez, D. A.
    Santangelo, A.
    Schlickeiser, R.
    Schulz, A.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Sheidaei, F.
    Skilton, J. L.
    Sol, H.
    Spengler, G.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Stinzing, F.
    Stycz, K.
    Sushch, I.
    Szostek, A.
    Tavernet, J. -P.
    Terrier, R.
    Tluczykont, M.
    Valerius, K.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Viana, A.
    Vincent, P.
    Voelk, H. J.
    Volpe, F.
    Vorobiov, S.
    Vorster, M.
    Wagner, S. J.
    Ward, M.
    White, R.
    Wierzcholska, A.
    Zacharias, M.
    Zajczyk, A.
    Zdziarski, A. A.
    Zech, A.
    Zechlin, H. -S.
    Discovery of gamma-ray emission from the extragalactic pulsar wind nebula N 157B with HESS2012Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 545, artikel-id L2Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    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 energised nebulae that emit gamma rays up to energies of several tens of TeV. N 157B is associated with PSR J0537-6910, which is the pulsar with the highest known spin-down luminosity. The High Energy Stereoscopic System telescope array observed this nebula on a yearly basis from 2004 to 2009 with a dead-time corrected exposure of 46 h. The gamma-ray spectrum between 600 GeV and 12 TeV is well-described by a pure power-law with a photon index of 2.8 +/- 0.2(stat) +/- 0.3(syst) and a normalisation at 1 TeV of (8.2 +/- 0.8(stat) +/- 2.5(syst)) x 10(-13) cm(-2) s(-1) TeV-1. A leptonic multi-wavelength model shows that an energy of about 4 x 10(49) erg is stored in electrons and positrons. The apparent efficiency, which is the ratio of the TeV gamma-ray luminosity to the pulsar's spin-down luminosity, 0.08% +/- 0.01%, is comparable to those of PWNe found in the Milky Way. The detection of a PWN at such a large distance is possible due to the pulsar's favourable spin-down luminosity and a bright infrared photon-field serving as an inverse-Compton-scattering target for accelerated leptons. By applying a calorimetric technique to these observations, the pulsar's birth period is estimated to be shorter than 10 ms.

  • 3. Abramowski, A.
    et al.
    Acero, F.
    Aharonian, F.
    Akhperjanian, A. G.
    Anton, G.
    Balzer, A.
    Barnacka, A.
    Becherini, Y.
    Becker, J.
    Bernloehr, K.
    Birsin, E.
    Biteau, J.
    Bochow, A.
    Boisson, C.
    Bolmont, J.
    Bordas, P.
    Brucker, J.
    Brun, F.
    Brun, P.
    Bulik, T.
    Buesching, I.
    Carrigan, S.
    Casanova, S.
    Cerruti, M.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Cologna, G.
    Conrad, J.
    Dalton, M.
    Daniel, M. K.
    Davids, I. D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O'C.
    Dubus, G.
    Dutson, K.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Eger, P.
    Espigat, P.
    Fallon, L.
    Fegan, S.
    Feinstein, F.
    Fernandes, M. V.
    Fiasson, A.
    Fontaine, G.
    Foerster, A.
    Fuessling, M.
    Gallant, Y. A.
    Gast, H.
    Gerard, L.
    Gerbig, D.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goering, D.
    Haeffner, S.
    Hague, J. D.
    Hahn, J.
    Hampf, D.
    Harris, J.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hillert, A.
    Hinton, J. A.
    Hofmann, W.
    Hofverberg, P.
    Holler, M.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jahn, C.
    Jamrozy, M.
    Jung, I.
    Kastendieck, M. A.
    Katarzynski, K.
    Katz, U.
    Kaufmann, S.
    Keogh, D.
    Khelifi, B.
    Klochkov, D.
    Kluzniak, W.
    Kneiske, T.
    Komin, Nu.
    Kosack, K.
    Kossakowski, R.
    Krayzel, F.
    Laffon, H.
    Lamanna, G.
    Lenain, J. -P.
    Lennarz, D.
    Lohse, T.
    Lopatin, A.
    Lu, C. -C.
    Marandon, V.
    Marcowith, A.
    Masbou, J.
    Maxted, N.
    Mayer, M.
    McComb, T. J. L.
    Medina, M. C.
    Mehault, J.
    Moderski, R.
    Mohamed, M.
    Moulin, E.
    Naumann, C. L.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Nguyen, N.
    Nicholas, B.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Wilhelmi, E. de Ona
    Opitz, B.
    Ostrowski, M.
    Oya, I.
    Panter, M.
    Arribas, M. Paz
    Pekeur, N. W.
    Pelletier, G.
    Perez, J.
    Petrucci, P. -O.
    Peyaud, B.
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Quirrenbach, A.
    Raue, M.
    Rayner, S. M.
    Reimer, A.
    Reimer, O.
    Renaud, M.
    de los Reyes, R.
    Rieger, F.
    Ripken, J.
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Sahakian, V.
    Sanchez, D. A.
    Santangelo, A.
    Schlickeiser, R.
    Schulz, A.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Sheidaei, F.
    Skilton, J. L.
    Sol, H.
    Spengler, G.
    Stawarz, L.
    Steenkamp, R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Stegmann, C.
    Stinzing, F.
    Stycz, K.
    Sushch, I.
    Szostek, A.
    Tavernet, J. -P.
    Terrier, R.
    Tluczykont, M.
    Valerius, K.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Viana, A.
    Vincent, P.
    Voelk, H. J.
    Volpe, F.
    Vorobiov, S.
    Vorster, M.
    Wagner, S. J.
    Ward, M.
    White, R.
    Wierzcholska, A.
    Zacharias, M.
    Zajczyk, A.
    Zdziarski, A. A.
    Zech, A.
    Zechlin, H. -S.
    Discovery of VHE gamma-ray emission and multi-wavelength observations of the BL Lacertae object 1RXSJ101015.9-3119092012Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 542, artikel-id A94Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    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 > 100 GeV) energies provide insights into the origin of very energetic particles present in such sources and the radiation processes at work. We report on results from VHE observations performed between 2006 and 2010 with the H. E. S. S. instrument, an array of four imaging atmospheric Cherenkov telescopes. H. E. S. S. data have been analysed with enhanced analysis methods, making the detection of faint sources more significant. VHE emission at a position coincident with 1RXS J101015.9-311909 is detected with H. E. S. S. for the first time. In a total good-quality livetime of about 49 h, we measure 263 excess counts, corresponding to a significance of 7.1 standard deviations. The photon spectrum above 0.2 TeV can be described by a power-law with a photon index of Gamma = 3.08 +/- 0.42(stat) +/- 0.20(sys). The integral flux above 0.2 TeV is about 0.8% of the flux of the Crab nebula and shows no significant variability over the time reported. In addition, public Fermi/LAT data are analysed to search for high energy emission from the source. The Fermi/LAT HE emission in the 100 MeV to 200 GeV energy range is significant at 8.3 standard deviations in the chosen 25-month dataset. UV and X-ray contemporaneous observations with the Swift satellite in May 2007 are also reported, together with optical observations performed with the atom telescope located at the H. E. S. S. site. Swift observations reveal an absorbed X-ray flux of F(0.3-7) keV = 1.04(-0.05)(+0.04) x 10(-11) erg cm(-2) s(-1) in the 0.3-7 keV range. Finally, all the available data are used to study the multi-wavelength properties of the source. The spectral energy distribution (SED) can be reproduced using a simple one-zone Synchrotron Self Compton (SSC) model with emission from a region with a Doppler factor of 30 and a magnetic field between 0.025 and 0.16 G. These parameters are similar to those obtained for other sources of this type.

  • 4. Abramowski, A.
    et al.
    Acero, F.
    Aharonian, F.
    Akhperjanian, A. G.
    Anton, G.
    Balzer, A.
    Barnacka, A.
    de Almeida, U. Barres
    Becherini, Y.
    Becker, J.
    Behera, B.
    Bernloehr, K.
    Birsin, E.
    Biteau, J.
    Bochow, A.
    Boisson, C.
    Bolmont, J.
    Bordas, P.
    Brucker, J.
    Brun, F.
    Brun, P.
    Bulik, T.
    Buesching, I.
    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.
    Cologna, G.
    Conrad, Jan M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Dalton, M.
    Daniel, M. K.
    Davids, I. D.
    Degrange, B.
    Deil, C.
    Dickinson, Hugh J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O'C.
    Dubois, F.
    Dubus, G.
    Dutson, K.
    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.
    Foerster, A.
    Fuessling, M.
    Gallant, Y. A.
    Gast, H.
    Gerard, L.
    Gerbig, D.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Goering, D.
    Haeffner, S.
    Hague, J. D.
    Hampf, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Hofverberg, P.
    Holler, M.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jahn, C.
    Jamrozy, M.
    Jung, I.
    Kastendieck, M. A.
    Katarzynski, K.
    Katz, U.
    Kaufmann, S.
    Keogh, D.
    Khangulyan, D.
    Khelifi, 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.
    Mayer, M.
    McComb, T. J. L.
    Medina, M. C.
    Mehault, J.
    Moderski, R.
    Moulin, E.
    Naumann, C. L.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Nguyen, N.
    Nicholas, B.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Wilhelmi, E. de Ona
    Opitz, B.
    Ostrowski, M.
    Oya, I.
    Panter, M.
    Arribas, M. Paz
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O.
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Quirrenbach, A.
    Raue, M.
    Rayner, S. M.
    Reimer, A.
    Reimer, O.
    Renaud, M.
    Reyes, R. de los
    Rieger, F.
    Ripken, Joachim
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Ruppel, J.
    Sahakian, V.
    Sanchez, D.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schulz, A.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Sheidaei, F.
    Sikora, M.
    Skilton, J. L.
    Sol, H.
    Spengler, G.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Stinzing, F.
    Stycz, K.
    Sushch, I.
    Szostek, A.
    Tavernet, J. -P.
    Terrier, R.
    Tluczykont, M.
    Valerius, K.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Vialle, J. P.
    Viana, A.
    Vincent, P.
    Voelk, H. J.
    Volpe, F.
    Vorobiov, S.
    Vorster, M.
    Wagner, S. J.
    Ward, M.
    White, R.
    Wierzcholska, A.
    Zacharias, M.
    Zajczyk, A.
    Zdziarski, A. A.
    Zech, A.
    Zechlin, H. -S.
    Discovery of extended VHE gamma-ray emission from the vicinity of the young massive stellar cluster Westerlund 12012Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 537, artikel-id A114Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aims. Results obtained in very-high-energy (VHE; E >= 100 GeV) gamma-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 cluster Westerlund 1 (Wd 1).

    Methods. Imaging of Cherenkov light from gamma-ray induced particle cascades in the Earth's atmosphere is used to search for VHE gamma rays from the region around Wd 1. Possible catalogued counterparts are searched for and discussed in terms of morphology and energetics of the H.E.S.S. source.

    Results. The detection of the degree-scale extended VHE gamma-ray source HESS J1646-458 is reported based on 45 h of H.E.S.S. observations performed between 2004 and 2008. The VHE gamma-ray source is centred on the nominal position of Wd 1 and detected with a total statistical significance of similar to 20 sigma. The emission region clearly extends beyond the H.E.S.S. point-spread function (PSF). The differential energy spectrum follows a power law in energy with an index of Gamma = 2.19 +/- 0.08(stat) +/- 0.20(sys) and a flux normalisation at 1 TeV of Phi(0) = (9.0 +/- 1.4(stat) +/- 1.8(sys)) x 10(-12) TeV-1 cm(-2) s(-1). The integral flux above 0.2 TeV amounts to (5.2 +/- 0.9) x 10(-11) cm(-2) s(-1).

    Conclusions. Four objects coincident with HESS J1646-458 are discussed in the search of a counterpart, namely the magnetar CXOU J164710.2-455216, the X-ray binary 4U 1642-45, the pulsar PSR J1648-4611 and the massive stellar cluster Wd 1. In a single-source scenario, Wd 1 is favoured as site of VHE particle acceleration. Here, a hadronic parent population would be accelerated within the stellar cluster. Beside this, there is evidence for a multi-source origin, where a scenario involving PSR J1648-4611 could be viable to explain parts of the VHE gamma-ray emission of HESS J1646-458.

  • 5. Abramowski, A.
    et al.
    Acero, F.
    Aharonian, F.
    Akhperjanian, A. G.
    Anton, G.
    Balzer, A.
    Barnacka, A.
    de Almeida, U. Barres
    Becherini, Y.
    Becker, J.
    Behera, B.
    Bernloehr, K.
    Birsin, E.
    Biteau, J.
    Bochow, A.
    Boisson, C.
    Bolmont, J.
    Bordas, P.
    Brucker, J.
    Brun, F.
    Brun, P.
    Bulik, T.
    Buesching, I.
    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.
    Cologna, G.
    Conrad, Jan M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Dalton, M.
    Daniel, M. K.
    Davids, I. D.
    Degrange, B.
    Deil, C.
    Dickinson, Hugh J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O'C.
    Dubois, F.
    Dubus, G.
    Dutson, K.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Eger, P.
    Espigat, P.
    Fallon, L.
    Farnier, C.
    Feinstein, F.
    Fernandes, M. V.
    Fiasson, A.
    Fontaine, G.
    Foerster, A.
    Fuessling, M.
    Gallant, Y. A.
    Gast, H.
    Gerard, L.
    Gerbig, D.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Goering, D.
    Haeffner, S.
    Hague, J. D.
    Hampf, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Hofverberg, P.
    Holler, M.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jahn, C.
    Jamrozy, M.
    Jung, I.
    Kastendieck, M. A.
    Katarzynski, K.
    Katz, U.
    Kaufmann, S.
    Keogh, D.
    Khangulyan, D.
    Khelifi, 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.
    Mayer, M.
    McComb, T. J. L.
    Medina, M. C.
    Mehault, J.
    Moderski, R.
    Moulin, E.
    Naumann, C. L.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Nguyen, N.
    Nicholas, B.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Wilhelmi, E. de Ona
    Opitz, B.
    Ostrowski, M.
    Oya, I.
    Panter, M.
    Arribas, M. Paz
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O.
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Quirrenbach, A.
    Raue, M.
    Rayner, S. M.
    Reimer, A.
    Reimer, O.
    Renaud, M.
    de los Reyes, R.
    Rieger, F.
    Ripken, Joachim
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Ruppel, J.
    Sahakian, V.
    Sanchez, D. A.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schulz, A.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Sheidaei, F.
    Sikora, M.
    Skilton, J. L.
    Sol, H.
    Spengler, G.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Stinzing, F.
    Stycz, K.
    Sushch, I.
    Szostek, A.
    Tavernet, J. -P.
    Terrier, R.
    Tluczykont, M.
    Valerius, K.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Vialle, J. P.
    Viana, A.
    Vincent, P.
    Voelk, H. J.
    Volpe, F.
    Vorobiov, S.
    Vorster, M.
    Wagner, S. J.
    Ward, M.
    White, R.
    Wierzcholska, A.
    Zacharias, M.
    Zajczyk, A.
    Zdziarski, A. A.
    Zech, A.
    Zechlin, H. -S.
    Costamante, L.
    Fegan, S.
    Ajello, M.
    Discovery of hard-spectrum gamma- ray emission from the BL Lacertae object 1ES 0414+0092012Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 538, artikel-id A103Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    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-highenergy (VHE, E > 100 GeV) gamma-rays due to its high X-ray and radio flux.

    Aims. Observations in the VHE gamma-ray band and across the electromagnetic spectrum can provide insights into the origin of highly energetic particles present in the source and the radiation processes at work. Because of the distance of the source, the gamma-ray spectrum might provide further limits on the level of the extragalactic background light (EBL).

    Methods. We report observations made between October 2005 and December 2009 with H. E. S. S., an array of four imaging atmospheric Cherenkov telescopes. Observations at high energies (HE, 100 MeV-100 GeV) with the Fermi-LAT instrument in the first 20 months of its operation are also reported. To complete the multi-wavelength picture, archival UV and X-ray observations with the Swift satellite and optical observations with the ATOM telescope are also used.

    Results. Based on the observations with H.E.S.S., 1ES 0414+009 is detected for the first time in the VHE band. An excess of 224 events is measured, corresponding to a significance of 7.8 sigma. The photon spectrum of the source is well described by a power law, with photon index of Gamma(VHE) = 3.45 +/- 0.25(stat) +/- 0.20(syst). The integral flux above 200 GeV is (1.88 +/- 0.20(stat) +/- 0.38(syst)) x10(-12) cm(-2) s(-1). Observations with the Fermi-LAT in the first 20 months of operation show a flux between 200 MeV and 100 GeV of (2.3 +/- 0.2(stat)) x 10(-9) erg cm(-2) s(-1), and a spectrum well described by a power-law function with a photon index Gamma(HE) = 1.85 +/- 0.18. Swift/XRT observations show an X-ray flux between 2 and 10 keV of (0.8-1) x 10(-11) erg cm(-2) s(-1), and a steep spectrum Gamma(X) = (2.2-2.3). Combining X-ray with optical-UV data, a fit with a log-parabolic function locates the synchrotron peak around 0.1 keV.

    Conclusions. Although the GeV-TeV observations do not provide better constraints on the EBL than previously obtained, they confirm a low density of the EBL, close to the lower limits from galaxy counts. The absorption-corrected HE and VHE gamma-ray spectra are both hard and have similar spectral indices (approximate to 1.86), indicating no significant change of slope between the HE and VHE gamma-ray bands, and locating the gamma-ray peak in the SED above 1-2 TeV. As for other TeV BL Lac objects with the gamma-ray peak at such high energies and a large separation between the two SED humps, this average broad-band SED represents a challenge for simple one-zone synchrotron self-Compton models, requiring a high Doppler factor and very low B-field.

  • 6. De Angelis, A.
    et al.
    Tatischeff, V.
    Grenier, I. A.
    McEnery, J.
    Mallamaci, M.
    Tavani, M.
    Oberlack, U.
    Hanlon, L.
    Walter, R.
    Argan, A.
    Von Ballmoos, P.
    Bulgarelli, A.
    Bykov, A.
    Hernanz, M.
    Kanbach, G.
    Kuvvetli, I.
    Pearce, M.
    Zdziarski, A.
    Conrad, Jan M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ghisellini, G.
    Harding, A.
    Isern, J.
    Leising, M.
    Longo, F.
    Madejski, G.
    Martinez, M.
    Mazziotta, M. N.
    Paredes, J. M.
    Pohl, M.
    Rando, R.
    Razzano, M.
    Aboudan, A.
    Ackermann, M.
    Addazi, A.
    Ajello, M.
    Albertus, C.
    Alvarez, J. M.
    Ambrosi, G.
    Anton, S.
    Antonelli, L. A.
    Babic, A.
    Baibussinov, B.
    Balbom, M.
    Baldini, L.
    Balman, S.
    Bambi, C.
    Barres de Almeida, U.
    Barrio, J. A.
    Bartels, R.
    Bastieri, D.
    Bednarek, W.
    Bernard, D.
    Bernardini, E.
    Bernasconi, T.
    Bertucci, B.
    Biland, A.
    Bissaldi, E.
    Boettcher, M.
    Bonvicini, V.
    Bosch-Ramon, V.
    Bottacini, E.
    Bozhilov, V.
    Bretz, T.
    Branchesi, M.
    Brdar, V.
    Bringmann, T.
    Brogna, A.
    Jorgensen, C. Budtz
    Busetto, G.
    Buson, S.
    Busso, M.
    Caccianiga, A.
    Camera, S.
    Campana, R.
    Caraveo, P.
    Cardillo, M.
    Carlson, P.
    Celestin, S.
    Cermeno, M.
    Chen, A.
    Cheung, C. C.
    Churazov, E.
    Ciprini, S.
    Coc, A.
    Colafrancesco, S.
    Coleiro, A.
    Collmar, W.
    Coppi, P.
    Curado da Silva, R.
    Cutini, S.
    D'Ammando, F.
    De Lotto, B.
    de Martino, D.
    De Rosa, A.
    Del Santo, M.
    Delgado, L.
    Diehl, R.
    Dietrich, S.
    Dolgov, A. D.
    Dominguez, A.
    Prester, D. Dominis
    Donnarumma, I.
    Dorner, D.
    Doro, M.
    Dutra, M.
    Elsaesser, D.
    Fabrizio, M.
    Fernandez-Barral, A.
    Fioretti, V.
    Foffano, L.
    Formato, V.
    Fornengo, N.
    Foschini, L.
    Franceschini, A.
    Franckowiak, A.
    Funk, S.
    Fuschino, F.
    Gaggero, D.
    Galanti, G.
    Gargano, F.
    Gasparrini, D.
    Gehrz, R.
    Giammaria, P.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Ghirlanda, G.
    Godinovic, N.
    Gouiffes, C.
    Grove, J. E.
    Hamadache, C.
    Hartmann, D. H.
    Hayashida, M.
    Hryczuk, A.
    Jean, P.
    Johnson, T.
    Jose, J.
    Kaufmann, S.
    Khelifi, B.
    Kiener, J.
    Knodlseder, J.
    Kolem, M.
    Kopp, J.
    Kozhuharov, V.
    Labanti, C.
    Lalkovski, S.
    Laurent, P.
    Limousin, O.
    Linares, M.
    Lindfors, E.
    Lindner, M.
    Liu, J.
    Lombardi, S.
    Loparco, F.
    Lopez-Coto, R.
    Lopez Moya, M.
    Lott, B.
    Lubrano, P.
    Malyshev, D.
    Mankuzhiyil, N.
    Mannheim, K.
    Marcha, M. J.
    Marciano, A.
    Marcote, B.
    Mariotti, M.
    Marisaldi, M.
    McBreen, S.
    Mereghetti, S.
    Merle, A.
    Mignani, R.
    Minervini, G.
    Moiseev, A.
    Morselli, A.
    Moura, F.
    Nakazawa, K.
    Nava, L.
    Nieto, D.
    Orienti, M.
    Orio, M.
    Orlando, E.
    Orleanski, P.
    Paiano, S.
    Paoletti, R.
    Papitto, A.
    Pasquato, M.
    Patricelli, B.
    Perez-Garcia, M. A.
    Persic, M.
    Piano, G.
    Pichel, A.
    Pimenta, M.
    Pittori, C.
    Porter, T.
    Poutanen, J.
    Prandini, E.
    Prantzos, N.
    Produit, N.
    Profumo, S.
    Queiroz, F. S.
    Raino, S.
    Raklev, A.
    Regis, M.
    Reichardt, I.
    Rephaeli, Y.
    Rico, J.
    Rodejohann, W.
    Fernandez, G. Rodriguez
    Roncadelli, M.
    Roso, L.
    Rovero, A.
    Ruffini, R.
    Sala, G.
    Sanchez-Conde, M. A.
    Santangelo, A.
    Parkinson, P. Saz
    Sbarrato, T.
    Shearer, A.
    Shellard, R.
    Short, K.
    Siegert, T.
    Siqueira, C.
    Spinelli, P.
    Stamerra, A.
    Starrfield, S.
    Strong, A.
    Strumke, I.
    Tavecchio, F.
    Taverna, R.
    Terzic, T.
    Thompson, D. J.
    Tibolla, O.
    Torres, D. F.
    Turolla, R.
    Ulyanov, A.
    Ursi, A.
    Vacchi, A.
    Van den Abeele, J.
    Vankova-Kirilovai, G.
    Venter, C.
    Verrecchia, F.
    Vincent, P.
    Wang, X.
    Weniger, C.
    Wu, X.
    Zaharijas, G.
    Zampieri, L.
    Zane, S.
    Zimmer, S.
    Zoglauer, A.
    Science with e-ASTROGAM A space mission for MeV-GeV gamma-ray astrophysics2018Ingår i: Journal of high energy astrophysics, ISSN 2214-4048, Vol. 19, s. 1-106Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    e-ASTROGAM ('enhanced ASTROGAM') is a breakthrough Observatory space mission, with a detector composed by a Silicon tracker, a calorimeter, and an anticoincidence system, dedicated to the study of the non-thermal Universe in the photon energy range from 0.3 MeV to 3 GeV - the lower energy limit can be pushed to energies as low as 150 keV for the tracker, and to 30 keV for calorimetric detection. The mission is based on an advanced space-proven detector technology, with unprecedented sensitivity, angular and energy resolution, combined with polarimetric capability. Thanks to its performance in the MeV-GeV domain, substantially improving its predecessors, e-ASTROGAM will open a new window on the non-thermal Universe, making pioneering observations of the most powerful Galactic and extragalactic sources, elucidating the nature of their relativistic outflows and their effects on the surroundings. With a line sensitivity in the MeV energy range one to two orders of magnitude better than previous generation instruments, e-ASTROGAM will determine the origin of key isotopes fundamental for the understanding of supernova explosion and the chemical evolution of our Galaxy. The mission will provide unique data of significant interest to a broad astronomical community, complementary to powerful observatories such as LIGO-Virgo-GEO600-KAGRA, SKA, ALMA, E-ELT, TMT, LSST, JWST, Athena, CTA, IceCube, KM3NeT, and LISA.

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