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Blazar 3C 454.3 in Outburst and Quiescence During 2005-2007: Two Variable Synchrotron Emission Peaks

Ogle, Patrick M. and Wehrle, Ann E. and Balonek, Thomas and Gurwell, Mark A. (2011) Blazar 3C 454.3 in Outburst and Quiescence During 2005-2007: Two Variable Synchrotron Emission Peaks. Astrophysical Journal Supplement Series, 195 (2). Art. No. 19. ISSN 0067-0049.

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We monitored the flaring blazar 3C 454.3 during 2005 June-July with the Spitzer Infrared Spectrograph (IRS: 15 epochs), Infrared Array Camera (IRAC: 12 epochs), and Multiband Imaging Photometer (MIPS: 2 epochs). We also made Spitzer IRS, IRAC, and MIPS observations from 2006 December to 2007 January when the source was in a low state, the latter simultaneous with a single Chandra X-ray observation. In addition, we present optical and submillimeter (sub-mm) monitoring data. The 2005-2007 period saw three major outbursts. We present evidence that the radio-optical spectral energy distribution (SED) actually consists of two variable synchrotron peaks, the primary at IR and the secondary at sub-mm wavelengths. The lag between the optical and sub-mm outbursts may indicate that these two peaks arise from two distinct regions along the jet separated by a distance of 0.9-3 pc. The flux at 5-35 μm varied by a factor of 40 and the IR peak varied in frequency from 4 × 10^(12) Hz to 4 × 10^(13) Hz between the highest and lowest states in 2005 and 2006, respectively. Variability was well correlated across the mid-IR band, with no measurable lag. Flares that doubled in flux occurred on a timescale of ~5 days, yielding a variability size of <0.05 pc. The IR SED peak moved to higher frequency as a flare brightened, then returned to lower frequency as it decayed. The fractional variability amplitude increased with frequency, which we attribute to decreasing synchrotron self-absorption optical depth. Mid-IR flares may signal the re-energization of a shock that runs into inhomogeneities along the pre-existing jet or in the external medium. The synchrotron peak frequencies during each major outburst may depend upon both the distance from the jet apex and the physical conditions in the shocks. Variation of the Doppler parameter along a curved or helical jet is another possibility. Frequency variability of the IR synchrotron peak may have important consequences for the interpretation of the blazar sequence, and the presence of a secondary peak may give insight into jet structure.

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Ogle, Patrick M.0000-0002-3471-981X
Additional Information:© 2011 The American Astronomical Society. Received 2010 March 16; accepted 2011 April 19; published 2011 August 3. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407. Optical observations at Palomar Observatory were made possible through the NASA Space Interferometry Mission Preparatory Science Program for the Key Project on Active Galactic Nuclei. Support for this work was provided by NASA through awards issued by JPL/Caltech. The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica. This work is partly based on data taken and assembled by the WEBT collaboration and stored in the WEBT archive at the Osservatorio Astronomico di Torino- INAF ( are grateful to Karl Gordon (Arizona) and Jason Surace (Spitzer Science Center) for assistance in processing MIPS and IRAC data, and to Booth Hartley for customizing IPAC Skyview for use on Intel Macs. We are grateful to Massimo Villata and Claudia Raiteri for providingWEBTdata and for helpful discussions, and to Bill Keel (U. of Alabama) and Marco Chiaberge (STScI) for working with us on the Hubble images. We have made use of data from the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.
Group:Infrared Processing and Analysis Center (IPAC)
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Smithsonian InstitutionUNSPECIFIED
Academia SinicaUNSPECIFIED
Subject Keywords:galaxies: jets; quasars: individual (3C 454.3)
Issue or Number:2
Classification Code:PACS: 98.54.cM; 98.62.Py; 98.54.Aj; 98.70.Dk; 98.62.Ai; 98.70.Qy; 98.62.Nx
Record Number:CaltechAUTHORS:20110928-102318056
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Official Citation:Blazar 3C 454.3 in Outburst and Quiescence during 2005-2007: Two Variable Synchrotron Emission Peaks Patrick M. Ogle et al. 2011 ApJS 195 19
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:25468
Deposited By: Ruth Sustaita
Deposited On:28 Sep 2011 17:55
Last Modified:03 Oct 2019 03:06

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