CaltechAUTHORS
Published March 2020 | Version Accepted Version + Published
Journal Article Open

Multiwavelength behaviour of the blazar 3C 279: decade-long study from γ-ray to radio

Creators

  • 1. ROR icon St Petersburg University
  • 2. ROR icon Pulkovo Observatory
  • 3. ROR icon Boston University
  • 4. ROR icon Osservatorio Astrofisico di Torino
  • 5. ROR icon University of Arizona
  • 6. ROR icon Instituto de Astrofísica de Andalucía
  • 7. ROR icon Instituto de Astrofísica de Canarias
  • 8. ROR icon University of La Laguna
  • 9. ROR icon University of Michigan–Ann Arbor
  • 10. ROR icon Institute of Applied Astronomy
  • 11. ROR icon Bulgarian Academy of Sciences
  • 12. ROR icon University of Siena
  • 13. ROR icon Sofia University
  • 14. ROR icon Osservatorio Astronomico della Regione Autonoma Valle d'Aosta
  • 15. ROR icon Max Planck Institute for Radio Astronomy
  • 16. ROR icon National Central University
  • 17. ROR icon Astronomical Observatory
  • 18. ROR icon Astronomical Observatory of Rome
  • 19. ROR icon Osservatorio Astrofisico di Catania
  • 20. ROR icon Agenzia Spaziale Italiana
  • 21. ROR icon Harvard-Smithsonian Center for Astrophysics
  • 22. ROR icon University of Turku
  • 23. ROR icon Aalto University
  • 24. ROR icon Shumen University
  • 25. ROR icon California Institute of Technology
  • 26. ROR icon Abastumani Astrophysical Observatory
  • 27. ROR icon Astro Space Center
  • 28. ROR icon Institute of Physics and Technology
  • 29. ROR icon Kazan Federal University
  • 30. ROR icon Heidelberg University
  • 31. ROR icon Osaka Kyoiku University
  • 32. ROR icon Special Astrophysical Observatory
  • 33. ROR icon Ulugh Beg Astronomical Institute
  • 34. ROR icon Istituto di Radioastronomia di Bologna
  • 35. ROR icon University of Colorado Boulder
  • 36. ROR icon Physical Research Laboratory
  • 37. ROR icon Institute of Astronomy and National Astronomical Observatory

Abstract

We report the results of decade-long (2008–2018) γ-ray to 1 GHz radio monitoring of the blazar 3C 279, including GASP/WEBT, Fermi and Swift data, as well as polarimetric and spectroscopic data. The X-ray and γ-ray light curves correlate well, with no delay ≳3 h, implying general cospatiality of the emission regions. The γ-ray–optical flux–flux relation changes with activity state, ranging from a linear to a more complex dependence. The behaviour of the Stokes parameters at optical and radio wavelengths, including 43 GHz Very Long Baseline Array images, supports either a predominantly helical magnetic field or motion of the radiating plasma along a spiral path. Apparent speeds of emission knots range from 10 to 37c, with the highest values requiring bulk Lorentz factors close to those needed to explain γ-ray variability on very short time-scales. The Mg II emission line flux in the 'blue' and 'red' wings correlates with the optical synchrotron continuum flux density, possibly providing a variable source of seed photons for inverse Compton scattering. In the radio bands, we find progressive delays of the most prominent light-curve maxima with decreasing frequency, as expected from the frequency dependence of the τ = 1 surface of synchrotron self-absorption. The global maximum in the 86 GHz light curve becomes less prominent at lower frequencies, while a local maximum, appearing in 2014, strengthens toward decreasing frequencies, becoming pronounced at ∼5 GHz. These tendencies suggest different Doppler boosting of stratified radio-emitting zones in the jet.

Additional Information

© 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). Received: 03 October 2019; Revision received: 12 December 2019; Accepted: 08 January 2020; Published: 11 January 2020. We thank the referee for attentive reading and comments that helped to improve presentation of the manuscript. The data collected by the WEBT collaboration are stored in the WEBT archive at the Osservatorio Astrofisico di Torino – INAF (http://www.oato.inaf.it/blazars/webt/); for questions regarding their availability, please contact the WEBT President Massimo Villata (massimo.villata@inaf.it). The St. Petersburg University team acknowledges support from Russian Science Foundation grant 17-12-01029. The research at BU was supported in part by National Science Foundation grant AST-1615796 and NASA Fermi Guest Investigator grants 80NSSC17K0649, 80NSSC19K1504, and 80NSSC19K1505. The PRISM camera at Lowell Observatory was developed by K. Janes et al. at BU and Lowell Observatory, with funding from the NSF, BU, and Lowell Observatory. The emission-line observations made use of the DCT at Lowell Observatory, supported by Discovery Communications, Inc., BU, the University of Maryland, the University of Toledo, and Northern Arizona University. The VLBA is an instrument of the National Radio Astronomy Observatory. The National Radio Astronomy Observatory is a facility of the US NSF, operated under cooperative agreement by Associated Universities, Inc. This research has used data from the UMRAO which was supported by the University of Michigan; research at this facility was supported by NASA under awards NNX09AU16G, NNX10AP16G, NNX11AO13G, and NNX13AP18G, and by the NSF under award AST-0607523. The Steward Observatory spectropolarimetric monitoring project was supported by NASA Fermi Guest Investigator grants NNX08AW56G, NNX09AU10G, NNX12AO93G, and NNX15AU81G. The Torino group acknowledges financial contribution from agreement ASI-INAF n.2017-14-H.0 and from contract PRIN-SKA-CTA-INAF 2016. I.A. acknowledges support by a Ramón y Cajal grant (RYC-2013-14511) of the 'Ministerio de Ciencia, Innovación, y Universidades (MICIU)' of Spain and from MCIU through the 'Center of Excellence Severo Ochoa' award for the Instituto de Astrofísica de Andalucía-CSIC (SEV-2017-0709). Acquisition and reduction of the POLAMI and MAPCAT data were supported by MICIU through grant AYA2016-80889-P. The POLAMI observations were carried out at the IRAM 30-m Telescope, supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). The MAPCAT observations were carried out at the German-Spanish Calar Alto Observatory, jointly operated by the Max-Plank-Institut für Astronomie and the Instituto de Astrofísica de Andalucía-CSIC. The study is based partly on data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated by AIP and IAC. The OVRO 40-m monitoring program is supported in part by NASA grants NNX08AW31G, NNX11A043G, and NNX14AQ89G, and NSF grants AST-0808050 and AST-1109911. TH was supported by the Academy of Finland projects 317383 and 320085. AZT-24 observations were made within an agreement between Pulkovo, Rome and Teramo observatories. 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. The Abastumani team acknowledges financial support by the Shota Rustaveli National Science Foundation under contract FR/217950/16. This research was partially supported by the Bulgarian National Science Fund of the Ministry of Education and Science under grants DN 08-1/2016, DN 18-13/2017, KP-06-H28/3 (2018), and KP-06-PN38/1 (2019), Bulgarian National Science Programme 'Young Scientists and Postdoctoral Students 2019', Bulgarian National Science Fund under grant DN18-10/2017 and National RI Roadmap Projects DO1-157/28.08.2018 and DO1-153/28.08.2018 of the Ministry of Education and Science of the Republic of Bulgaria. GD and OV gratefully acknowledge observing grant support from the Institute of Astronomy and Rozhen National Astronomical Observatory via bilateral joint research project 'Study of ICRF radio-sources and fast variable astronomical objects' (head – G. Damljanovic). This work was partly supported by the National Science Fund of the Ministry of Education and Science of Bulgaria under grant DN 08-20/2016, and by project RD-08-37/2019 of the University of Shumen. This work is a part of projects nos 176011, 176004, and 176021, supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia. MGM acknowledges support through the Russian Government Program of Competitive Growth of Kazan Federal University. The Astronomical Observatory of the Autonomous Region of the Aosta Valley (OAVdA) is managed by the Fondazione Clément Fillietroz-ONLUS, which is supported by the Regional Government of the Aosta Valley, the Town Municipality of Nus and the 'Unité des Communes valdôtaines Mont-Émilius'. The research at the OAVdA was partially funded by several 'Research and Education' annual grants from Fondazione CRT. This article is partly based on observations made with the IAC80 and TCS telescopes operated by the Instituto de Astrofísica de Canarias in the Spanish Observatorio del Teide on the island of Tenerife. A part of the observations were carried out using the RATAN-600 scientific equipment (SAO of the Russian Academy of Sciences).

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Additional details

Identifiers

Eprint ID
102136
Resolver ID
CaltechAUTHORS:20200327-073401845

Related works

Describes
https://arxiv.org/abs/2001.06512 (URL)

Funding

Russian Science Foundation
17-12-01029
NSF
AST-1615796
NASA
80NSSC17K0649
NASA
80NSSC19K1504
NASA
80NSSC19K1505
NASA
NNX09AU16G
NASA
NNX10AP16G
NASA
NNX11AO13G
NASA
NNX13AP18G
NSF
AST-0607523
NASA
NNX08AW56G
NASA
NNX09AU10G
NASA
NNX12AO93G
NASA
NNX15AU81G
Agenzia Spaziale Italiana (ASI)
2017-14-H.0
Istituto Nazionale di Astrofisica (INAF)
CTA-INAF 2016
Ramón y Cajal Programme
RYC-2013-14511
Severo Ochoa
SEV-2017-0709
Ministerio de Economía, Industria y Competitividad (MINECO)
AYA2016-80889-P
NASA
NNX08AW31G
NASA
NNX11A043G
NASA
NNX14AQ89G
NSF
AST-0808050
NSF
AST-1109911
Academy of Finland
317383
Academy of Finland
320085
Shota Rustaveli National Science Foundation
FR/217950/16
Ministry of Education and Science (Bulgaria)
DN 08-1/2016
Ministry of Education and Science (Bulgaria)
DN 18-13/2017
Ministry of Education and Science (Bulgaria)
KP-06-H28/3
Ministry of Education and Science (Bulgaria)
KP-06-PN38/1
Bulgarian National Science Programme
Bulgarian National Science Fund
DN18-10/2017
Ministry of Education and Science (Bulgaria)
DO1-157/28.08.2018
Ministry of Education and Science (Bulgaria)
DO1-153/28.08.2018
Institute of Astronomy
Rozhen National Astronomical Observatory
Ministry of Education and Science (Bulgaria)
DN 08-20/2016
University of Shumen
RD-08-37/2019
Ministry of Education, Science and Technological Development (Serbia)
176011
Ministry of Education, Science and Technological Development (Serbia)
176004
Ministry of Education, Science and Technological Development (Serbia)
176021
Kazan Federal University

Dates

Created
2020-03-27
Created from EPrint's datestamp field
Updated
2021-11-16
Created from EPrint's last_modified field