Rapid variability of blazar 3C 279 during flaring states in 2013−2014 with joint Fermi-LAT, NuSTAR, Swift, and ground-based multi-wavelength observations

Journal Article · Wed Jul 01 00:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/807/1/79· OSTI ID:22882945

Hayashida, M. ^[1]; Nalewajko, K.; Madejski, G. M.; Blandford, R. D.; Chiang, J.; Furniss, A. K. ^[2]; Sikora, M. ^[3]; Itoh, R.; Fukazawa, Y. ^[4]; Ajello, M. ^[5]; Buson, S. ^[6]; Urry, C. M.; Hasan, I. ^[7]; Harrison, F. A.; Baloković, M. ^[8]; Alexander, D. M. ^[9]; Barret, D. ^[10]; Boggs, S. E. ^[11]; Christensen, F. E. ^[12]; others, and

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1. Institute for Cosmic Ray Research, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8582 (Japan)
2. 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)
3. Nicolaus Copernicus Astronomical Center, 00-716 Warsaw (Poland)
4. Department of Physical Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)
5. Department of Physics and Astronomy, Clemson University, Kinard Lab of Physics, Clemson, SC 29634-0978 (United States)
6. Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy)
7. Yale Center for Astronomy and Astrophysics, Physics Department, Yale University, PO Box 208120, New Haven, CT 06520-8120 (United States)
8. Cahill Center for Astronomy and Astrophysics, Caltech, Pasadena, CA 91125 (United States)
9. Department of Physics, Durham University, Durham DH1 3LE (United Kingdom)
10. Université de Toulouse, UPS—OMP, IRAP, Toulouse (France)
11. Space Science Laboratory, University of California, Berkeley, CA 94720 (United States)
12. DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark)

We report the results of a multiband observing campaign on the famous blazar 3C 279 conducted during a phase of increased activity from 2013 December to 2014 April, including first observations of it with NuSTAR. The γ-ray emission of the source measured by Fermi-LAT showed multiple distinct flares reaching the highest flux level measured in this object since the beginning of the Fermi mission, with F(E>100 MeV) of 10{sup −5} photons cm{sup −2} s{sup −1}, and with a flux-doubling time scale as short as 2 hr. The γ-ray spectrum during one of the flares was very hard, with an index of Γ{sub γ}=1.7±0.1, which is rarely seen in flat-spectrum radio quasars. The lack of concurrent optical variability implies a very high Compton dominance parameter L{sub γ}/L{sub syn}>300. Two 1 day NuSTAR observations with accompanying Swift pointings were separated by 2 weeks, probing different levels of source activity. While the 0.5−70 keV X-ray spectrum obtained during the first pointing, and fitted jointly with Swift-XRT is well-described by a simple power law, the second joint observation showed an unusual spectral structure: the spectrum softens by ΔΓ{sub X}≃0.4 at ∼4 keV. Modeling the broadband spectral energy distribution during this flare with the standard synchrotron plus inverse-Compton model requires: (1) the location of the γ-ray emitting region is comparable with the broad-line region radius, (2) a very hard electron energy distribution index p≃1, (3) total jet power significantly exceeding the accretion-disk luminosity L{sub j}/L{sub d}≳10, and (4) extremely low jet magnetization with L{sub B}/L{sub j}≲10{sup −4}. We also find that single-zone models that match the observed γ-ray and optical spectra cannot satisfactorily explain the production of X-ray emission.

• OSTI ID: 22882945
• Journal Information: Astrophysical Journal, Vol. 807, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ACCRETION DISKS
COMPARATIVE EVALUATIONS
COMPTON EFFECT
ELECTRONS
EMISSION
ENERGY SPECTRA
GAMMA RADIATION
KEV RANGE 01-10
LUMINOSITY
MAGNETIZATION
MEV RANGE 100-1000
QUASARS
SIMULATION
SYNCHROTRON RADIATION
X RADIATION
X-RAY GALAXIES
X-RAY SPECTRA