Detection of the gamma-ray binary LS I +61 303 in a low flux state at Very High Energy gamma-rays with the MAGIC Telescopes in 2009
Creators: name: MAGIC Collaboration
name: Aleksić, J.
name: Alvarez, E. A.
name: Antonelli, L. A.
name: Antoranz, P.
name: Asensio, M.
name: Backes, M.
name: Barrio, J. A.
name: Bastieri, D.
name: González, J. Becerra
name: Bednarek, W.
name: Berdyugin, A.
name: Berger, K.
name: Bernardini, E.
name: Biland, A.
name: Blanch, O.
name: Bock, R. K.
name: Boller, A.
name: Bonnoli, G.
name: Tridon, D. Borla
name: Bosch-Ramon, V.
name: Braun, I.
name: Bretz, T.
name: Cañellas, A.
name: Carmona, E.
name: Carosi, A.
name: Colin, P.
name: Colombo, E.
name: Contreras, J. L.
name: Cortina, J.
name: Cossio, L.
name: Covino, S.
name: Dazzi, F.
name: De Angelis, A.
name: De Caneva, G.
name: del Pozo, E. De Cea
name: De Lotto, B.
name: Mendez, C. Delgado
name: Ortega, A. Diago
name: Doert, M.
name: Domínguez, A.
name: Prester, D. Dominis
name: Dorner, D.
name: Doro, M.
name: Elsaesser, D.
name: Ferenc, D.
name: Fonseca, M. V.
name: Font, L.
name: Fruck, C.
name: López, R. J. García
name: Garczarczyk, M.
name: Garrido, D.
name: Giavitto, G.
name: Godinović, N.
name: Hadasch, D.
name: Häfner, D.
name: Herrero, A.
name: Hildebrand, D.
name: Höhne-Mönch, D.
name: Hose, J.
name: Hrupec, D.
name: Huber, B.
name: Jogler, T.
name: Kellermann, H.
name: Klepser, S.
name: Krähenbühl, T.
name: Krause, J.
name: La Barbera, A.
name: Lelas, D.
name: Leonardo, E.
name: Lindfors, E.
name: Lombardi, S.
name: López, M.
name: López-Oramas, A.
name: Lorenz, E.
name: Makariev, M.
name: Maneva, G.
name: Mankuzhiyil, N.
name: Mannheim, K.
name: Maraschi, L.
name: Mariotti, M.
name: Martínez, M.
name: Mazin, D.
name: Meucci, M.
name: Miranda, J. M.
name: Mirzoyan, R.
name: Miyamoto, H.
name: Moldón, J.
name: Moralejo, A.
name: Munar-Adrover, P.
name: Nieto, D.
name: Nilsson, K.
name: Orito, R.
name: Oya, I.
name: Paneque, D.
name: Paoletti, R.
name: Pardo, S.
name: Paredes, J. M.
name: Partini, S.
name: Pasanen, M.
name: Pauss, F.
name: Perez-Torres, M. A.
name: Persic, M.
name: Peruzzo, L.
name: Pilia, M.
name: Pochon, J.
name: Prada, F.
name: Moroni, P. G. Prada
name: Prandini, E.
name: Puljak, I.
name: Reichardt, I.
name: Reinthal, R.
name: Rhode, W.
name: Ribó, M.
name: Rico, J.
name: Rügamer, S.
name: Saggion, A.
name: Saito, K.
name: Saito, T. Y.
name: Salvati, M.
name: Satalecka, K.
name: Scalzotto, V.
name: Scapin, V.
name: Schultz, C.
name: Schweizer, T.
name: Shayduk, M.
name: Shore, S. N.
name: Sillanpää, A.
name: Sitarek, J.
name: Sobczynska, D.
name: Spanier, F.
name: Spiro, S.
name: Stamatescu, V.
name: Stamerra, A.
name: Steinke, B.
name: Storz, J.
name: Strah, N.
name: Surić, T.
name: Takalo, L.
name: Takami, H.
name: Tavecchio, F.
name: Temnikov, P.
name: Terzić, T.
name: Tescaro, D.
name: Teshima, M.
name: Tibolla, O.
name: Torres, D. F.
name: Treves, A.
name: Uellenbeck, M.
name: Vankov, H.
name: Vogler, P.
name: Wagner, R. M.
name: Weitzel, Q.
name: Zabalza, V.
name: Zandanel, F.
name: Zanin, R.
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We present very high energy (VHE, E &gt; 100 GeV) γ-ray observations of the γ-ray binary system LS I+61 303 obtained with the MAGIC stereo system between 2009 October and 2010 January. We detect a 6.3σ γ-ray signal above 400 GeV in the combined data set. The integral flux above an energy of 300 GeV is F(E&gt;300 GeV)=(1.4 +- 0.3stat +- 0.4syst) * 10^{-12} cm^{-2} s^{-1}, which corresponds to about 1.3% of the Crab Nebula flux in the same energy range. The orbit-averaged flux of LS I +61 303 in the orbital phase interval 0.6--0.7, where a maximum of the TeV flux is expected, is lower by almost an order of magnitude compared to our previous measurements between 2005 September and 2008 January. This provides evidence for a new low emission state in LS I +61 303. We find that the change to the low flux state cannot be solely explained by an increase of photon-photon absorption around the compact star.
description: Corresponding authors: T. Jogler and O. Blanch; accepted for publication in ApJ, 6 pages and 3 figures