MAGIC Collaboration, : J. Aleksić, E. A. Alvarez, L. A. Antonelli, P. Antoranz, M. Asensio, M. Backes, J. A. Barrio, D. Bastieri, J. Becerra González, W. Bednarek, A. Berdyugin, K. Berger, E. Bernardini, A. Biland, O. Blanch, R. K. Bock, A. Boller, G. Bonnoli, D. Borla Tridon, I. Braun, T. Bretz, A. Cañellas, E. Carmona, A. Carosi, P. Colin, E. Colombo, J. L. Contreras, J. Cortina, L. Cossio, S. Covino, F. Dazzi, A. De Angelis, G. De Caneva, E. De Cea del Pozo, B. De Lotto, C. Delgado Mendez, A. Diago Ortega, M. Doert, A. Domínguez, D. Dominis Prester, D. Dorner, M. Doro, D. Elsaesser, D. Ferenc, M. V. Fonseca, L. Font, C. Fruck, R. J. García López, M. Garczarczyk, D. Garrido, G. Giavitto, N. Godinović, D. Hadasch, D. Häfner, A. Herrero, D. Hildebrand, D. Höhne-Mönch, J. Hose, D. Hrupec, B. Huber, T. Jogler, H. Kellermann, S. Klepser, T. Krähenbühl, J. Krause, A. La Barbera, D. Lelas, E. Leonardo, E. Lindfors, S. Lombardi, M. López, A. López-Oramas, E. Lorenz, M. Makariev, G. Maneva, N. Mankuzhiyil, K. Mannheim, L. Maraschi, M. Mariotti, M. Martínez, D. Mazin, M. Meucci, J. M. Miranda, R. Mirzoyan, H. Miyamoto, J. Moldón, A. Moralejo, P. Munar-Adrover, D. Nieto, K. Nilsson, R. Orito, I. Oya, D. Paneque, R. Paoletti, S. Pardo, J. M. Paredes, S. Partini, M. Pasanen, F. Pauss, M. A. Perez-Torres, M. Persic, L. Peruzzo, M. Pilia, J. Pochon, F. Prada, P. G. Prada Moroni, E. Prandini, I. Puljak, I. Reichardt, R. Reinthal, W. Rhode, M. Ribó, J. Rico, S. Rügamer, A. Saggion, K. Saito, T. Y. Saito, M. Salvati, K. Satalecka, V. Scalzotto, V. Scapin, C. Schultz, T. Schweizer, M. Shayduk, S. N. Shore, A. Sillanpää, J. Sitarek, D. Sobczynska, F. Spanier, S. Spiro, V. Stamatescu, A. Stamerra, B. Steinke, J. Storz, N. Strah, T. Surić, L. Takalo, H. Takami, F. Tavecchio, P. Temnikov, T. Terzić, D. Tescaro, M. Teshima, O. Tibolla, D. F. Torres, A. Treves, M. Uellenbeck, H. Vankov, P. Vogler, R. M. Wagner, Q. Weitzel, V. Zabalza, F. Zandanel, R. Zanin, S. Buson, D. Horan, S. Larsson, F. D'Ammando
We present the results of five years (2005-2009) of MAGIC observations of the
BL Lac object PG 1553+113 at very high energies (VHEs, E > 100 GeV). Power law
fits of the individual years are compatible with a steady mean photon index
\Gamma = 4.27 $\pm$ 0.14. In the last three years of data, the flux level above
150 GeV shows a clear variability (probability of constant flux < 0.001%). The
flux variations are modest, lying in the range from 4% to 11% of the Crab
Nebula flux. Simultaneous optical data also show only modest variability that
seems to be correlated with VHE gamma ray variability. We also performed a
temporal analysis of (all available) simultaneous Fermi/LAT data of PG 1553+113
above 1 GeV, which reveals hints of variability in the 2008-2009 sample.
Finally, we present a combination of the mean spectrum measured at very high
energies with archival data available for other wavelengths. The mean spectral
energy distribution can be modeled with a one-zone Synchrotron Self Compton
(SSC) model, which gives the main physical parameters governing the VHE
emission in the blazar jet.
View original:
http://arxiv.org/abs/1101.2764
No comments:
Post a Comment