Please use this identifier to cite or link to this item: http://hdl.handle.net/2445/150423
 Title: PG 1553+113: five years of observations with MAGIC Author: Paredes i Poy, Josep MariaRibó Gomis, MarcMunar i Adrover, Pere Keywords: Raigs gammaGalàxiesGamma raysGalaxies Issue Date: 5-Mar-2012 Publisher: Institute of Physics (IOP) Abstract: 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. Note: Reproducció del document publicat a: https://doi.org/10.1088/0004-637X/748/1/46 It is part of: Astrophysical Journal, 2012, vol. 748, num. 1, p. 46A URI: http://hdl.handle.net/2445/150423 Related resource: https://doi.org/10.1088/0004-637X/748/1/46 ISSN: 0004-637X Appears in Collections: Articles publicats en revistes (Física Quàntica i Astrofísica)

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