@article {2012ApJ...746..151A, title = {{The 2010 Very High Energy {$\gamma$}-Ray Flare and 10 Years of Multi-wavelength Observations of M 87}}, journal = {The Astrophysical Journal}, volume = {746}, year = {2012}, month = {feb}, pages = {151}, abstract = {The giant radio galaxy M 87 with its proximity (16 Mpc), famous jet, and very massive black hole ((3 - 6) {\times} 10$^{9}$ M $_{\&sun;}$) provides a unique opportunity to investigate the origin of very high energy (VHE; E {\gt} 100 GeV) {$\gamma$}-ray emission generated in relativistic outflows and the surroundings of supermassive black holes. M 87 has been established as a VHE {$\gamma$}-ray emitter since 2006. The VHE {$\gamma$}-ray emission displays strong variability on timescales as short as a day. In this paper, results from a joint VHE monitoring campaign on M 87 by the MAGIC and VERITAS instruments in 2010 are reported. During the campaign, a flare at VHE was detected triggering further observations at VHE (H.E.S.S.), X-rays (Chandra), and radio (43 GHz Very Long Baseline Array, VLBA). The excellent sampling of the VHE {$\gamma$}-ray light curve enables one to derive a precise temporal characterization of the flare: the single, isolated flare is well described by a two-sided exponential function with significantly different flux rise and decay times of {$\tau$}$^{rise}$ $_{d}$ = (1.69 {\plusmn} 0.30) days and {$\tau$}$^{decay}$ $_{d}$ = (0.611 {\plusmn} 0.080) days, respectively. While the overall variability pattern of the 2010 flare appears somewhat different from that of previous VHE flares in 2005 and 2008, they share very similar timescales (\~{}day), peak fluxes ({$\Phi$}$_{>0.35 TeV}$ \~{}= (1-3) {\times} 10$^{-11}$ photons cm$^{-2}$ s$^{-1}$), and VHE spectra. VLBA radio observations of 43 GHz of the inner jet regions indicate no enhanced flux in 2010 in contrast to observations in 2008, where an increase of the radio flux of the innermost core regions coincided with a VHE flare. On the other hand, Chandra X-ray observations taken \~{}3 days after the peak of the VHE {$\gamma$}-ray emission reveal an enhanced flux from the core (flux increased by factor \~{}2; variability timescale {\l}t}2 days). The long-term (2001-2010) multi-wavelength (MWL) light curve of M 87, spanning from radio to VHE and including data from Hubble Space Telescope, Liverpool Telescope, Very Large Array, and European VLBI Network, is used to further investigate the origin of the VHE {$\gamma$}-ray emission. No unique, common MWL signature of the three VHE flares has been identified. In the outer kiloparsec jet region, in particular in HST-1, no enhanced MWL activity was detected in 2008 and 2010, disfavoring it as the origin of the VHE flares during these years. Shortly after two of the three flares (2008 and 2010), the X-ray core was observed to be at a higher flux level than its characteristic range (determined from more than 60 monitoring observations: 2002-2009). In 2005, the strong flux dominance of HST-1 could have suppressed the detection of such a feature. Published models for VHE {$\gamma$}-ray emission from M 87 are reviewed in the light of the new data.}, keywords = {galaxies: active, galaxies: individual: M 87, galaxies: jets, galaxies: nuclei, gamma rays: galaxies, radiation mechanisms: non-thermal}, doi = {10.1088/0004-637X/746/2/151}, url = {http://adsabs.harvard.edu/abs/2012ApJ...746..151A}, author = {Abramowski, A. and Acero, F. and Aharonian, F. and Akhperjanian, A.~G. and Anton, G. and Balzer, A. and Barnacka, A. and Barres de Almeida, U. and Becherini, Y. and Becker, J. and Behera, B. and Bernl{\"o}hr, K. and Birsin, E. and Biteau, J. and Bochow, A. and Boisson, C. and Bolmont, J. and Bordas, P. and Brucker, J. and Brun, F. and Brun, P. and Bulik, T. and B{\"u}sching, I. and Carrigan, S. and Casanova, S. and Cerruti, M. and Chadwick, P.~M. and Charbonnier, A. and Chaves, R.~C.~G. and Cheesebrough, A. and Clapson, A.~C. and Coignet, G. and Cologna, G. and Conrad, J. and Dalton, M. and Daniel, M.~K. and Davids, I.~D. and Degrange, B. and Deil, C. and Dickinson, H.~J. and Djannati-Ata{\"\i}, A. and Domainko, W. and Drury, L.~O. and Dubus, G. and Dutson, K. and Dyks, J. and Dyrda, M. and Egberts, K. and Eger, P. and Espigat, P. and Fallon, L. and Farnier, C. and Fegan, S. and Feinstein, F. and Fernandes, M.~V. and Fiasson, A. and Fontaine, G. and F{\"o}rster, A. and F{\"u}{\ss}ling, M. and Gallant, Y.~A. and Gast, H. and G{\'e}rard, L. and Gerbig, D. and Giebels, B. and Glicenstein, J.~F. and Gl{\"u}ck, B. and Goret, P. and G{\"o}ring, D. and H{\"a}ffner, S. and Hague, J.~D. and Hampf, D. and Hauser, M. and Heinz, S. and Heinzelmann, G. and Henri, G. and Hermann, G. and Hinton, J.~A. and Hoffmann, A. and Hofmann, W. and Hofverberg, P. and Holler, M. and Horns, D. and Jacholkowska, A. and de Jager, O.~C. and Jahn, C. and Jamrozy, M. and Jung, I. and Kastendieck, M.~A. and Katarzy{\'n}ski, K. and Katz, U. and Kaufmann, S. and Keogh, D. and Khangulyan, D. and Kh{\'e}lifi, B. and Klochkov, D. and Klu{\'z}niak, W. and Kneiske, T. and Komin, N. and Kosack, K. and Kossakowski, R. and Laffon, H. and Lamanna, G. and Lennarz, D. and Lohse, T. and Lopatin, A. and Lu, C.-C. and Marandon, V. and Marcowith, A. and Masbou, J. and Maurin, D. and Maxted, N. and Mayer, M. and McComb, T.~J.~L. and Medina, M.~C. and M{\'e}hault, J. and Moderski, R. and Moulin, E. and Naumann, C.~L. and Naumann-Godo, M. and de Naurois, M. and Nedbal, D. and Nekrassov, D. and Nguyen, N. and Nicholas, B. and Niemiec, J. and Nolan, S.~J. and Ohm, S. and de O{\~n}a Wilhelmi, E. and Opitz, B. and Ostrowski, M. and Oya, I. and Panter, M. and Paz Arribas, M. and Pedaletti, G. and Pelletier, G. and Petrucci, P.-O. and Pita, S. and P{\"u}hlhofer, G. and Punch, M. and Quirrenbach, A. and Raue, M. and Rayner, S.~M. and Reimer, A. and Reimer, O. and Renaud, M. and de los Reyes, R. and Rieger, F. and Ripken, J. and Rob, L. and Rosier-Lees, S. and Rowell, G. and Rudak, B. and Rulten, C.~B. and Ruppel, J. and Sahakian, V. and Sanchez, D.~A. and Santangelo, A. and Schlickeiser, R. and Sch{\"o}ck, F.~M. and Schulz, A. and Schwanke, U. and Schwarzburg, S. and Schwemmer, S. and Sheidaei, F. and Skilton, J.~L. and Sol, H. and Spengler, G. and Stawarz, {\L}. and Steenkamp, R. and Stegmann, C. and Stinzing, F. and Stycz, K. and Sushch, I. and Szostek, A. and Tavernet, J.-P. and Terrier, R. and Tluczykont, M. and Valerius, K. and van Eldik, C. and Vasileiadis, G. and Venter, C. and Vialle, J.~P. and Viana, A. and Vincent, P. and V{\"o}lk, H.~J. and Volpe, F. and Vorobiov, S. and Vorster, M. and Wagner, S.~J. and Ward, M. and White, R. and Wierzcholska, A. and Zacharias, M. and Zajczyk, A. and Zdziarski, A.~A. and Zech, A. and Zechlin, H.-S. and H.E.S.S.~Collaboration and Aleksi{\'c}, J. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Braun, I. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Huber, B. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lindfors, E. and Lombardi, S. and L{\'o}pez, M. and Lorenz, E. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Munar, P. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paneque, D. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Suri{\'c}, T. and Takalo, L. and Takami, H. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Thom, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Vankov, H. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R. and MAGIC Collaboration and Arlen, T. and Aune, T. and Beilicke, M. and Benbow, W. and Bouvier, A. and Bradbury, S.~M. and Buckley, J.~H. and Bugaev, V. and Byrum, K. and Cannon, A. and Cesarini, A. and Ciupik, L. and Connolly, M.~P. and Cui, W. and Dickherber, R. and Duke, C. and Errando, M. and Falcone, A. and Finley, J.~P. and Finnegan, G. and Fortson, L. and Furniss, A. and Galante, N. and Gall, D. and Godambe, S. and Griffin, S. and Grube, J. and Gyuk, G. and Hanna, D. and Holder, J. and Huan, H. and Hui, C.~M. and Kaaret, P. and Karlsson, N. and Kertzman, M. and Khassen, Y. and Kieda, D. and Krawczynski, H. and Krennrich, F. and Lang, M.~J. and LeBohec, S. and Maier, G. and McArthur, S. and McCann, A. and Moriarty, P. and Mukherjee, R. and Nu{\~n}ez, P.~D. and Ong, R.~A. and Orr, M. and Otte, A.~N. and Park, N. and Perkins, J.~S. and Pichel, A. and Pohl, M. and Prokoph, H. and Ragan, K. and Reyes, L.~C. and Reynolds, P.~T. and Roache, E. and Rose, H.~J. and Ruppel, J. and Schroedter, M. and Sembroski, G.~H. and \c Sent{\"u}rk, G.~D. and Telezhinsky, I. and Te\v si{\'c}, G. and Theiling, M. and Thibadeau, S. and Varlotta, A. and Vassiliev, V.~V. and Vivier, M. and Wakely, S.~P. and Weekes, T.~C. and Williams, D.~A. and Zitzer, B. and VERITAS Collaboration and Barres de Almeida, U. and Cara, M. and Casadio, C. and Cheung, C.~C. and McConville, W. and Davies, F. and Doi, A. and Giovannini, G. and Giroletti, M. and Hada, K. and Hardee, P. and Harris, D.~E. and Junor, W. and Kino, M. and Lee, N.~P. and Ly, C. and Madrid, J. and Massaro, F. and Mundell, C.~G. and Nagai, H. and Perlman, E.~S. and Steele, I.~A. and Walker, R.~C. and Wood, D.~L.} } @article {2011ApJ...730L...8A, title = {{MAGIC Discovery of Very High Energy Emission from the FSRQ PKS 1222+21}}, journal = {The Astrophysical Journal Letters}, volume = {730}, year = {2011}, month = {mar}, pages = {L8}, abstract = {{Very high energy (VHE) {$\gamma$}-ray emission from the flat spectrum radio quasar (FSRQ) PKS 1222+21 (4C 21.35}, keywords = {cosmic background radiation, galaxies: active, galaxies: jets, gamma rays: galaxies, quasars: individual: PKS 1222+21}, doi = {10.1088/2041-8205/730/1/L8}, url = {http://adsabs.harvard.edu/abs/2011ApJ...730L...8A}, author = {Aleksi{\'c}, J. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Braun, I. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Huber, B. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lindfors, E. and Lombardi, S. and L{\'o}pez, M. and Lorenz, E. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paneque, D. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Thom, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Vankov, H. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R. and MAGIC Collaboration and Tanaka, Y.~T. and Wood, D.~L. and Buson, S.} } @article {2011A\&A...530A...4A, title = {{MAGIC Observations and multiwavelength properties of the quasar 3C 279 in 2007 and 2009}}, journal = {Astronomy and Astrophysics}, volume = {530}, year = {2011}, month = {jun}, pages = {A4}, abstract = {Context. 3C 279, the first quasar discovered to emit VHE {$\gamma$}-rays by the MAGIC telescope in 2006, was reobserved by MAGIC in January 2007 during a major optical flare and from December 2008 to April 2009 following an alert from the Fermi space telescope on an exceptionally high {$\gamma$}-ray state.
Aims: The January 2007 observations resulted in a detection on January 16 with significance 5.4{$\sigma$}, corresponding to a F ({\gt}150 GeV) (3.8 {\plusmn} 0.8) {\times} 10$^{-11}$ ph cm$^{-2}$ s$^{-1}$ while the overall data sample does not show significant signal. The December 2008-April 2009 observations did not detect the source. We study the multiwavelength behaviour of the source at the epochs of MAGIC observations, collecting quasi-simultaneous data at optical and X-ray frequencies and for 2009 also {$\gamma$}-ray data from Fermi.
Methods: We study the light curves and spectral energy distribution of the source. The spectral energy distributions of three observing epochs (including the February 2006, which has been previously published) are modelled with one-zone inverse Compton models and the emission on January 16, 2007 also with two zone model and with a lepto-hadronic model.
Results: We find that the VHE {$\gamma$}-ray emission detected in 2006 and 2007 challenges standard one-zone model, based on relativistic electrons in a jet scattering broad line region photons, while the other studied models fit the observed spectral energy distribution more satisfactorily.}, keywords = {gamma rays: galaxies, quasars: individual: 3C 279}, doi = {10.1051/0004-6361/201116497}, url = {http://adsabs.harvard.edu/abs/2011A\%26A...530A...4A}, author = {Aleksi{\'c}, J. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Braun, I. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and Hose, J. and Hrupec, D. and Huber, B. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lindfors, E. and Lombardi, S. and L{\'o}pez, M. and Lorenz, E. and Majumdar, P. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and R{\"u}ger, M. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Thom, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Vankov, H. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R.} } @article {2011ApJ...726...58A, title = {{Observations of the Blazar 3C 66A with the Magic Telescopes in Stereoscopic Mode}}, journal = {The Astrophysical Journal}, volume = {726}, year = {2011}, month = {jan}, pages = {58}, abstract = {We report new observations of the intermediate-frequency peaked BL Lacertae object 3C 66A with the MAGIC telescopes. The data sample we use were taken in 2009 December and 2010 January, and comprises 2.3 hr of good quality data in stereoscopic mode. In this period, we find a significant signal from the direction of the blazar 3C 66A. The new MAGIC stereoscopic system is shown to play an essential role for the separation between 3C 66A and the nearby radio galaxy 3C 66B, which is at a distance of only 6{\textquoteright}. The derived integral flux above 100 GeV is 8.3\% of the Crab Nebula flux and the energy spectrum is reproduced by a power law of photon index 3.64 {\plusmn} 0.39$_{stat}$ {\plusmn} 0.25$_{sys}$. Within errors, this is compatible with the one derived by VERITAS in 2009. From the spectra corrected for absorption by the extragalactic background light, we only find small differences between the four models that we applied, and constrain the redshift of the blazar to z {\l}t} 0.68.}, keywords = {BL Lacertae objects: individual: 3C 66A, galaxies: active, gamma rays: galaxies}, doi = {10.1088/0004-637X/726/2/58}, url = {http://adsabs.harvard.edu/abs/2011ApJ...726...58A}, author = {Aleksi{\'c}, J. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Bordas, P. and Borla Tridon, D. and Bosch-Ramon, V. and Bose, D. and Braun, I. and Bretz, T. and Camara, M. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and De Lotto, B. and De Maria, M. and De Sabata, F. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Errando, M. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Kranich, D. and Krause, J. and La Barbera, A. and Leonardo, E. and Lindfors, E. and Lombardi, S. and Longo, F. and L{\'o}pez, M. and Lorenz, E. and Majumdar, P. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paoletti, R. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and Pegna, R.~G. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puchades, N. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and S{\'a}nchez-Conde, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sierpowska-Bartosik, A. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Struebig, J.~C. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Thom, M. and Torres, D.~F. and Vankov, H. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R.} } @article {2011ApJ...735L...5A, title = {{A Search for Very High Energy Gamma-Ray Emission from Scorpius X-1 with the Magic Telescopes}}, journal = {The Astrophysical Journal Letters}, volume = {735}, year = {2011}, month = {jul}, pages = {L5}, abstract = {The acceleration of particles up to GeV or higher energies in microquasars has been the subject of considerable theoretical and observational efforts in the past few years. Sco X-1 is a microquasar from which evidence of highly energetic particles in the jet has been found when it is in the so-called Horizontal Branch (HB), a state when the radio and hard X-ray fluxes are higher and a powerful relativistic jet is present. Here we present the first very high energy gamma-ray observations of Sco X-1, obtained with the MAGIC telescopes. An analysis of the whole data set does not yield a significant signal, with 95\% CL flux upper limits above 300 GeV at the level of 2.4 {\times} 10$^{-12}$ cm$^{-2}$ s$^{-1}$. Simultaneous RXTE observations were conducted to provide the X-ray state of the source. A selection of the gamma-ray data obtained during the HB based on the X-ray colors did not yield a signal either, with an upper limit of 3.4 {\times} 10$^{-12}$ cm$^{-2}$ s$^{-1}$. These upper limits place a constraint on the maximum TeV luminosity to non-thermal X-ray luminosity of L $_{VHE}$/L $_{ntX}$ {\l}t}\~{} 0.02 that can be related to a maximum TeV luminosity to jet power ratio of L $_{VHE}$/L $_{j}$ {\l}t}\~{} 10$^{-3}$. Our upper limits indicate that the underlying high-energy emission physics in Sco X-1 must be inherently different from that of the hitherto detected gamma-ray binaries.}, keywords = {acceleration of particles, gamma rays: stars, stars: individual: Sco X-1, X-rays: binaries}, doi = {10.1088/2041-8205/735/1/L5}, url = {http://adsabs.harvard.edu/abs/2011ApJ...735L...5A}, author = {Aleksi{\'c}, J. and Alvarez, E.~A. and Antonelli, L.~A. and Antoranz, P. and Asensio, M. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Bordas, P. and Borla Tridon, D. and Bosch-Ramon, V. and Braun, I. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Huber, B. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lindfors, E. and Lombardi, S. and L{\'o}pez, M. and Lorenz, E. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Munar-Adrover, P. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paneque, D. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Suri{\'c}, T. and Takalo, L. and Takami, H. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Thom, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Vankov, H. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R.} } @article {2011JCAP...06..035A, title = {{Searches for dark matter annihilation signatures in the Segue 1 satellite galaxy with the MAGIC-I telescope}}, journal = {Journal of Cosmology and Astroparticle Physics}, volume = {6}, year = {2011}, month = {jun}, pages = {35}, abstract = {We report the results of the observation of the nearby satellite galaxy Segue 1 performed by the MAGIC-I ground-based gamma-ray telescope between November 2008 and March 2009 for a total of 43.2 hours. No significant gamma-ray emission was found above the background. Differential upper limits on the gamma-ray flux are derived assuming various power-law slopes for the possible emission spectrum. Integral upper limits are also calculated for several power-law spectra and for different energy thresholds. The values are of the order of 10$^{-11}$ ph cm$^{-2}$ s$^{-1}$ above 100 GeV and 10$^{-12}$ ph cm$^{-2}$ s$^{-1}$ above 200 GeV. Segue 1 is currently considered one of the most interesting targets for indirect dark matter searches. In these terms, the upper limits have been also interpreted in the context of annihilating dark matter particles. For such purpose, we performed a grid scan over a reasonable portion of the parameter space for the minimal SuperGravity model and computed the flux upper limit for each point separately, taking fully into account the peculiar spectral features of each model. We found that in order to match the experimental upper limits with the model predictions, a minimum flux boost of 10$^{3}$ is required, and that the upper limits are quite dependent on the shape of the gamma-ray energy spectrum predicted by each specific model. Finally we compared the upper limits with the predictions of some dark matter models able to explain the PAMELA rise in the positron ratio, finding that Segue 1 data are in tension with the dark matter explanation of the PAMELA spectrum in the case of a dark matter candidate annihilating into {$\tau$}$^{+}${$\tau$}$^{-}$. A complete exclusion however is not possible due to the uncertainties in the Segue 1 astrophysical factor.}, doi = {10.1088/1475-7516/2011/06/035}, url = {http://adsabs.harvard.edu/abs/2011JCAP...06..035A}, author = {Aleksi{\'c}, J. and Alvarez, E.~A. and Antonelli, L.~A. and Antoranz, P. and Asensio, M. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Braun, I. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Huber, B. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lindfors, E. and Lombardi, S. and L{\'o}pez, M. and Lorenz, E. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Munar-Androver, P. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paiano, S. and Paneque, D. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Suri{\'c}, T. and Takalo, L. and Takami, H. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Thom, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Vankov, H. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R. and Fornasa, M. and Essig, R. and Sehgal, N. and Strigari, L.~E.} }