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Title: Fermi Large Area Telescope detection of bright γ-ray outbursts from the peculiar quasar 4C +21.35

Abstract

In this study, 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 themore » 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 lesssim 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 (~10 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 (~10 19 cm).« less

Authors:
 [1];  [2];  [3];  [4];  [5];  [6];  [7];  [8];  [7];  [9];  [10];  [1];  [1];  [1];  [11];  [12];  [13];  [14];  [15];  [15] more »;  [16] « less
  1. Institute of Space and Astronautical Science, Kanagawa (Japan)
  2. Institute of Space and Astronautical Science, Kanagawa (Japan); Jagiellonian Univ., Krakow (Poland)
  3. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
  4. IASF Palermo, Palermo (Italy); INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, Roma (Italy)
  5. Ecole Polytechnique, Palaiseau (France)
  6. Univ. Bordeaux, Gradignan (France)
  7. Naval Research Lab., Washington, D.C. (United States)
  8. National Academy of Science, Washington, D.C. (United States); Naval Research Lab., Washington, D.C. (United States)
  9. Istituto Nazionale di Fisica Nucleare, Padova (Italy); Univ. di Padova, Padova (Italy)
  10. Univ. Bordeaux, Gradignan (France); Centre d'Etudes Nucleaires Bordeaux Gradignan, Gradignan (France)
  11. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Univ. of Maryland, College Park, MD (United States)
  12. Stanford Univ., Stanford, CA (United States)
  13. INAF Istituto di Radioastronomia, Bologna (Italy)
  14. Max-Planck-Institut fur Radioastronomie, Bonn (Germany)
  15. Istituto Nazionale di Fisica Nucleare, Trieste (Italy); Osservatorio Astronomico di Trieste, Trieste (Italy)
  16. Univ. degli Studi di Perugia, Perugia (Italy)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1357257
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Accepted Manuscript
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 733; Journal Issue: 1; Journal ID: ISSN 0004-637X
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; galaxies: active; galaxies: jets; gamma rays: galaxies; quasars: general; quasars: individual (4C +21.35); radiation mechanisms: non-thermal

Citation Formats

Tanaka, Y. T., Stawarz, Ł., Thompson, D. J., D'Ammando, F., Fegan, S. J., Lott, B., Wood, D. L., Cheung, C. C., Finke, J., Buson, S., Escande, L., Saito, S., Ohno, M., Takahashi, T., Donato, D., Chiang, J., Giroletti, M., Schinzel, F. K., Iafrate, G., Longo, F., and Ciprini, S. Fermi Large Area Telescope detection of bright γ-ray outbursts from the peculiar quasar 4C +21.35. United States: N. p., 2011. Web. doi:10.1088/0004-637X/733/1/19.
Tanaka, Y. T., Stawarz, Ł., Thompson, D. J., D'Ammando, F., Fegan, S. J., Lott, B., Wood, D. L., Cheung, C. C., Finke, J., Buson, S., Escande, L., Saito, S., Ohno, M., Takahashi, T., Donato, D., Chiang, J., Giroletti, M., Schinzel, F. K., Iafrate, G., Longo, F., & Ciprini, S. Fermi Large Area Telescope detection of bright γ-ray outbursts from the peculiar quasar 4C +21.35. United States. doi:10.1088/0004-637X/733/1/19.
Tanaka, Y. T., Stawarz, Ł., Thompson, D. J., D'Ammando, F., Fegan, S. J., Lott, B., Wood, D. L., Cheung, C. C., Finke, J., Buson, S., Escande, L., Saito, S., Ohno, M., Takahashi, T., Donato, D., Chiang, J., Giroletti, M., Schinzel, F. K., Iafrate, G., Longo, F., and Ciprini, S. Fri . "Fermi Large Area Telescope detection of bright γ-ray outbursts from the peculiar quasar 4C +21.35". United States. doi:10.1088/0004-637X/733/1/19. https://www.osti.gov/servlets/purl/1357257.
@article{osti_1357257,
title = {Fermi Large Area Telescope detection of bright γ-ray outbursts from the peculiar quasar 4C +21.35},
author = {Tanaka, Y. T. and Stawarz, Ł. and Thompson, D. J. and D'Ammando, F. and Fegan, S. J. and Lott, B. and Wood, D. L. and Cheung, C. C. and Finke, J. and Buson, S. and Escande, L. and Saito, S. and Ohno, M. and Takahashi, T. and Donato, D. and Chiang, J. and Giroletti, M. and Schinzel, F. K. and Iafrate, G. and Longo, F. and Ciprini, S.},
abstractNote = {In this study, 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 lesssim 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 (~1017 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 (~1019 cm).},
doi = {10.1088/0004-637X/733/1/19},
journal = {Astrophysical Journal},
number = 1,
volume = 733,
place = {United States},
year = {2011},
month = {4}
}

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