Multifrequency studies of the peculiar quasar 4C +21.35 during the 2010 flaring activity

Journal Article · Sat May 10 04:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/786/2/157· OSTI ID:22356912

Ackermann, M.; Buehler, R. ^[1]; Ajello, M. ^[2]; Allafort, A.; Caliandro, G. A.; Cameron, R. A. ^[3]; Antolini, E.; Bonamente, E.; Cecchi, C. ^[4]; Barbiellini, G. ^[5]; Bastieri, D.; Buson, S. ^[6]; Bellazzini, R.; Bregeon, J. ^[7]; Bissaldi, E. ^[8]; Brigida, M. ^[9]; Bruel, P. ^[10]; Caraveo, P. A. ^[11]; Cavazzuti, E. ^[12]; Chaves, R. C. G., ^[13] ; others, and

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1. Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany)
2. Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720-7450 (United States)
3. 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)
4. Dipartimento di Fisica, Università degli Studi di Perugia, I-06123 Perugia (Italy)
5. Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy)
6. Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy)
7. Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy)
8. Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, and Università di Trieste, I-34127 Trieste (Italy)
9. Dipartimento di Fisica "M. Merlin" dell'Università e del Politecnico di Bari, I-70126 Bari (Italy)
10. Laboratoire Leprince-Ringuet, École polytechnique, CNRS/IN2P3, Palaiseau (France)
11. INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, I-20133 Milano (Italy)
12. Agenzia Spaziale Italiana (ASI) Science Data Center, I-00044 Frascati (Roma) (Italy)
13. Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d'Astrophysique, CEA Saclay, F-91191 Gif sur Yvette (France)

The discovery of rapidly variable Very High Energy (VHE; E > 100 GeV) γ-ray emission from 4C +21.35 (PKS 1222+216) by MAGIC on 2010 June 17, triggered by the high activity detected by the Fermi Large Area Telescope (LAT) in high energy (HE; E > 100 MeV) γ-rays, poses intriguing questions on the location of the γ-ray emitting region in this flat spectrum radio quasar. We present multifrequency data of 4C +21.35 collected from centimeter to VHE during 2010 to investigate the properties of this source and discuss a possible emission model. The first hint of detection at VHE was observed by MAGIC on 2010 May 3, soon after a γ-ray flare detected by Fermi-LAT that peaked on April 29. The same emission mechanism may therefore be responsible for both the HE and VHE emission during the 2010 flaring episodes. Two optical peaks were detected on 2010 April 20 and June 30, close in time but not simultaneous with the two γ-ray peaks, while no clear connection was observed between the X-ray and γ-ray emission. An increasing flux density was observed in radio and mm bands from the beginning of 2009, in accordance with the increasing γ-ray activity observed by Fermi-LAT, and peaking on 2011 January 27 in the mm regime (230 GHz). We model the spectral energy distributions (SEDs) of 4C +21.35 for the two periods of the VHE detection and a quiescent state, using a one-zone model with the emission coming from a very compact region outside the broad line region. The three SEDs can be fit with a combination of synchrotron self-Compton and external Compton emission of seed photons from a dust torus, changing only the electron distribution parameters between the epochs. The fit of the optical/UV part of the spectrum for 2010 April 29 seems to favor an inner disk radius of

• OSTI ID: 22356912
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 786; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BLACK HOLES
DETECTION
DISTRIBUTION
DUSTS
ELECTRONS
EMISSION
ENERGY SPECTRA
FLUX DENSITY
GALAXIES
GAMMA RADIATION
GEV RANGE
GHZ RANGE
KERR FIELD
MEV RANGE
PHOTONS
QUASARS
SYNCHROTRONS
X RADIATION