FERMI LARGE AREA TELESCOPE DETECTION OF BRIGHT {gamma}-RAY OUTBURSTS FROM THE PECULIAR QUASAR 4C +21.35
- Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan)
- NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
- IASF Palermo, 90146 Palermo (Italy)
- Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS/IN2P3, Palaiseau (France)
- Universite Bordeaux 1, CNRS/IN2p3, Centre d'Etudes Nucleaires de Bordeaux Gradignan, 33175 Gradignan (France)
- Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)
- National Research Council Research Associate, National Academy of Sciences, Washington, DC 20001 (United States)
- Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy)
- Center for Research and Exploration in Space Science and Technology (CRESST) and NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
- W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)
- INAF Istituto di Radioastronomia, 40129 Bologna (Italy)
- Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany)
- Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy)
In this paper, we report on the two-year-long Fermi-Large Area Telescope observation of the peculiar blazar 4C +21.35 (PKS 1222+216). This source was in a quiescent state from the start of the science operations of the Fermi Gamma-ray Space Telescope in 2008 August until 2009 September, and then became more active, with gradually increasing flux and some moderately bright flares. In 2010 April and June, 4C +21.35 underwent a very strong GeV outburst composed of several major flares characterized by rise and decay timescales of the order of a day. During the outburst, the GeV spectra of 4C +21.35 displayed a broken power-law form with spectral breaks observed near 1-3 GeV photon energies. We demonstrate that, at least during the major flares, the jet in 4C +21.35 carried a total kinetic luminosity comparable to the total accretion power available to feed the outflow. We also discuss the origin of the break observed in the flaring spectra of 4C +21.35. We show that, in principle, a model involving annihilation of the GeV photons on the He II Lyman recombination continuum and line emission of 'broad-line region' clouds may account for such. However, we also discuss the additional constraint provided by the detection of 4C +21.35 at 0.07-0.4 TeV energies by the MAGIC telescope, which coincided with one of the GeV flares of the source. We argue that there are reasons to believe that the {approx}< TeV emission of 4C +21.35 (as well as the GeV emission of the source, if co-spatial) is not likely to be produced inside the broad-line region zone of highest ionization ({approx}10{sup 17} cm from the nucleus), but instead originates further away from the active center, namely, around the characteristic scale of the hot dusty torus surrounding the 4C +21.35 nucleus ({approx}10{sup 19} cm).
- OSTI ID:
- 21576800
- Journal Information:
- Astrophysical Journal, Vol. 733, Issue 1; Other Information: DOI: 10.1088/0004-637X/733/1/19; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Multifrequency studies of the peculiar quasar 4C +21.35 during the 2010 flaring activity
Multifrequency studies of the peculiar quasar 4C + 21.35 during the 2010 flaring activity