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Title: Rapid variability of blazar 3C 279 during flaring states in 2013-2014 with joint FERMI-LAT, NuSTAR, SWIFT, and ground-based multi-wavelength observations

Here 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 -5 photons cm -2 s -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 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 γ/L 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 x $$\simeq$$ 0.4 at ~ 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 $$\simeq$$ 1, (3) total jet power significantly exceeding the accretion-disk luminosity L j/L d ≳ 10, and (4) extremely low jet magnetization with L B/L j ≲ 10 -4. In conclusion, 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.
Authors:
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Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 807; Journal Issue: 1; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Contributing Orgs:
Fermi-LAT Collaboration
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS
OSTI Identifier:
1354932

Hayashida, M., Nalewajko, K., Madejski, G. M., Sikora, M., Itoh, R., Ajello, M., Blandford, R. D., Buson, S., Chiang, J., Fukazawa, Y., Furniss, A. K., Urry, C. M., Hasan, I., Harrison, F. A., Alexander, D. M., Baloković, M., Barret, D., Boggs, S. E., Christensen, F. E., Craig, W. W., Forster, K., Giommi, P., Grefenstette, B., Hailey, C., Hornstrup, A., Kitaguchi, T., Koglin, J. E., Madsen, K. K., Mao, P. H., Miyasaka, H., Mori, K., Perri, M., Pivovaroff, M. J., Puccetti, S., Rana, V., Stern, D., Tagliaferri, G., Westergaard, N. J., Zhang, W. W., Zoglauer, A., Gurwell, M. A., Uemura, M., Akitaya, H., Kawabata, K. S., Kawaguchi, K., Kanda, Y., Moritani, Y., Takaki, K., Ui, T., Yoshida, M., Agarwal, A., and Gupta, A. C.. Rapid variability of blazar 3C 279 during flaring states in 2013-2014 with joint FERMI-LAT, NuSTAR, SWIFT, and ground-based multi-wavelength observations. United States: N. p., Web. doi:10.1088/0004-637X/807/1/79.
Hayashida, M., Nalewajko, K., Madejski, G. M., Sikora, M., Itoh, R., Ajello, M., Blandford, R. D., Buson, S., Chiang, J., Fukazawa, Y., Furniss, A. K., Urry, C. M., Hasan, I., Harrison, F. A., Alexander, D. M., Baloković, M., Barret, D., Boggs, S. E., Christensen, F. E., Craig, W. W., Forster, K., Giommi, P., Grefenstette, B., Hailey, C., Hornstrup, A., Kitaguchi, T., Koglin, J. E., Madsen, K. K., Mao, P. H., Miyasaka, H., Mori, K., Perri, M., Pivovaroff, M. J., Puccetti, S., Rana, V., Stern, D., Tagliaferri, G., Westergaard, N. J., Zhang, W. W., Zoglauer, A., Gurwell, M. A., Uemura, M., Akitaya, H., Kawabata, K. S., Kawaguchi, K., Kanda, Y., Moritani, Y., Takaki, K., Ui, T., Yoshida, M., Agarwal, A., & Gupta, A. C.. Rapid variability of blazar 3C 279 during flaring states in 2013-2014 with joint FERMI-LAT, NuSTAR, SWIFT, and ground-based multi-wavelength observations. United States. doi:10.1088/0004-637X/807/1/79.
Hayashida, M., Nalewajko, K., Madejski, G. M., Sikora, M., Itoh, R., Ajello, M., Blandford, R. D., Buson, S., Chiang, J., Fukazawa, Y., Furniss, A. K., Urry, C. M., Hasan, I., Harrison, F. A., Alexander, D. M., Baloković, M., Barret, D., Boggs, S. E., Christensen, F. E., Craig, W. W., Forster, K., Giommi, P., Grefenstette, B., Hailey, C., Hornstrup, A., Kitaguchi, T., Koglin, J. E., Madsen, K. K., Mao, P. H., Miyasaka, H., Mori, K., Perri, M., Pivovaroff, M. J., Puccetti, S., Rana, V., Stern, D., Tagliaferri, G., Westergaard, N. J., Zhang, W. W., Zoglauer, A., Gurwell, M. A., Uemura, M., Akitaya, H., Kawabata, K. S., Kawaguchi, K., Kanda, Y., Moritani, Y., Takaki, K., Ui, T., Yoshida, M., Agarwal, A., and Gupta, A. C.. 2015. "Rapid variability of blazar 3C 279 during flaring states in 2013-2014 with joint FERMI-LAT, NuSTAR, SWIFT, and ground-based multi-wavelength observations". United States. doi:10.1088/0004-637X/807/1/79. https://www.osti.gov/servlets/purl/1354932.
@article{osti_1354932,
title = {Rapid variability of blazar 3C 279 during flaring states in 2013-2014 with joint FERMI-LAT, NuSTAR, SWIFT, and ground-based multi-wavelength observations},
author = {Hayashida, M. and Nalewajko, K. and Madejski, G. M. and Sikora, M. and Itoh, R. and Ajello, M. and Blandford, R. D. and Buson, S. and Chiang, J. and Fukazawa, Y. and Furniss, A. K. and Urry, C. M. and Hasan, I. and Harrison, F. A. and Alexander, D. M. and Baloković, M. and Barret, D. and Boggs, S. E. and Christensen, F. E. and Craig, W. W. and Forster, K. and Giommi, P. and Grefenstette, B. and Hailey, C. and Hornstrup, A. and Kitaguchi, T. and Koglin, J. E. and Madsen, K. K. and Mao, P. H. and Miyasaka, H. and Mori, K. and Perri, M. and Pivovaroff, M. J. and Puccetti, S. and Rana, V. and Stern, D. and Tagliaferri, G. and Westergaard, N. J. and Zhang, W. W. and Zoglauer, A. and Gurwell, M. A. and Uemura, M. and Akitaya, H. and Kawabata, K. S. and Kawaguchi, K. and Kanda, Y. and Moritani, Y. and Takaki, K. and Ui, T. and Yoshida, M. and Agarwal, A. and Gupta, A. C.},
abstractNote = {Here 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 10-5 photons cm-2 s-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 Γγ =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 Lγ/Lsyn > 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 ΔΓx $\simeq$ 0.4 at ~ 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 $\simeq$ 1, (3) total jet power significantly exceeding the accretion-disk luminosity Lj/Ld ≳ 10, and (4) extremely low jet magnetization with LB/Lj ≲ 10-4. In conclusion, 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.},
doi = {10.1088/0004-637X/807/1/79},
journal = {The Astrophysical Journal (Online)},
number = 1,
volume = 807,
place = {United States},
year = {2015},
month = {7}
}