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Detection of Very High Energy Radiation from the BL Lacertae Object PG 1553+113 with the MAGIC Telescope
J. Albert1, E. Aliu2, H. Anderhub3, P. Antoranz4, A. Armada2, C. Baixeras5, J. A. Barrio4, H. Bartko6, D. Bastieri7, J. Becker8, W. Bednarek9, K. Berger1, C. Bigongiari7, A. Biland3, R. K. Bock6,7, P. Bordas10, V. Bosch-Ramon10, T. Bretz1, I. Britvitch3, M. Camara4, E. Carmona6, A. Chilingarian11, S. Ciprini12, J. A. Coarasa6, S. Commichau3, J. L. Contreras4, J. Cortina2, V. Curtef8, V. Danielyan11, F. Dazzi7, A. De Angelis13, R. de los Reyes4, B. De Lotto13, E. Domingo-Santamaría2, D. Dorner1, M. Doro7, M. Errando2, M. Fagiolini14, D. Ferenc15, E. Fernández2, R. Firpo2, J. Flix2, M. V. Fonseca4, L. Font5, M. Fuchs6, N. Galante6, M. Garczarczyk6, M. Gaug7, M. Giller9, F. Goebel6, D. Hakobyan11, M. Hayashida6, T. Hengstebeck16, D. Höhne1, J. Hose6, C. C. Hsu6, P. Jacon9, T. Jogler6, O. Kalekin16, R. Kosyra6, D. Kranich3,17, R. Kritzer1, A. Laille15, P. Liebing6, E. Lindfors12, S. Lombardi7, F. Longo13, J. López2, M. López4, E. Lorenz3,6, P. Majumdar6, G. Maneva18, K. Mannheim1, O. Mansutti13, M. Mariotti7, M. Martínez2, D. Mazin6, C. Merck6, M. Meucci14, M. Meyer1, J. M. Miranda4, R. Mirzoyan6, S. Mizobuchi6, A. Moralejo2, K. Nilsson12, J. Ninkovic6, E. Oña-Wilhelmi2, N. Otte6, I. Oya4, D. Paneque6, R. Paoletti14, J. M. Paredes10, M. Pasanen12, D. Pascoli7, F. Pauss3, R. Pegna14, M. Persic13,19, L. Peruzzo17, A. Piccioli14, M. Poller1, N. Puchades2, E. Prandini7, A. Raymers11, W. Rhode8, M. Ribó10, J. Rico2, M. Rissi3, A. Robert5, S. Rügamer1, A. Saggion7, A. Sánchez5, P. Sartori7, V. Scalzotto7, V. Scapin7, R. Schmitt1, T. Schweizer6, M. Shayduk6,16, K. Shinozaki6, N. Sidro2, A. Sillanpää12, D. Sobczynska9, A. Stamerra14, L. S. Stark3, L. Takalo12, P. Temnikov18, D. Tescaro2, M. Teshima6, N. Tonello6, D. F. Torres2, N. Turini14, H. Vankov18, V. Vitale13, R. M. Wagner6,17, T. Wibig9, W. Wittek6, R. Zanin7, and J. Zapatero5
In 2005 and 2006, the MAGIC telescope observed very high energy gamma-ray emission from the distant BL Lac object PG 1553+113. The overall significance of the signal was 8.8 σ for 18.8 hr of observation time. The light curve shows no significant flux variations on a daily timescale; the flux level during 2005 was, however, significantly higher compared to 2006. The differential energy spectrum between ~90 and 500 GeV is well described by a power law with photon index Γ = 4.2 ± 0.3. The combined 2005 and 2006 energy spectrum provides an upper limit of z = 0.74 on the redshift of the object.
