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Published December 2024 | Version Published
Journal Article Open

A wiggling filamentary jet at the origin of the blazar multi-wavelength behaviour

Creators

  • 1. ROR icon Osservatorio Astrofisico di Torino
  • 2. ROR icon Abastumani Astrophysical Observatory
  • 3. ROR icon Ulugh Beg Astronomical Institute
  • 4. ROR icon National Autonomous University of Mexico
  • 5. ROR icon Brera Astronomical Observatory
  • 6. EPT Observatories, Tijarafe, La Palma, Spain
  • 7. INAF, TNG Fundación Galileo Galilei, La Palma, Spain
  • 8. ROR icon Instituto de Astrofísica de Canarias
  • 9. ROR icon Instituto de Astrofísica de Andalucía
  • 10. ROR icon Institute of Applied Astronomy
  • 11. Radioastronomical Observatory "Svetloe", 188833, Leningradskaya Oblast, Priozerskiy district, village Svetloe, Russia
  • 12. ROR icon Brigham Young University
  • 13. ROR icon Bulgarian Academy of Sciences
  • 14. Crimean Astrophysical Observatory RAS, P/O Nauchny, 298409, Crimea
  • 15. ROR icon Sofia University
  • 16. ROR icon Connecticut College
  • 17. ROR icon National Central University
  • 18. ROR icon Astronomical Observatory
  • 19. ROR icon National University of Uzbekistan
  • 20. Hans-Haffner-Sternwarte (Hettstadt), Naturwissenschaftliches Labor für Schüler, Friedrich-Koenig-Gymnasium, D-97082, Würzburg, Germany
  • 21. ROR icon TU Dortmund University
  • 22. Hypatia Observatory, 19 Via Sacco e Vanzetti, Viserba, Rimini, Italy
  • 23. ROR icon National and Kapodistrian University of Athens
  • 24. ROR icon Istituto di Radioastronomia di Bologna
  • 25. ROR icon St Petersburg University
  • 26. ROR icon Aryabhatta Research Institute of Observational Sciences
  • 27. ROR icon Xinjiang Astronomical Observatory
  • 28. ROR icon Harvard-Smithsonian Center for Astrophysics
  • 29. ROR icon National Research Institute of Astronomy and Geophysics
  • 30. ROR icon California Institute of Technology
  • 31. ROR icon Boston University
  • 32. ROR icon University of Crete
  • 33. ROR icon Astro Space Center
  • 34. ROR icon Institute for Nuclear Research
  • 35. ROR icon Max Planck Institute for Radio Astronomy
  • 36. ROR icon Kazan Federal University
  • 37. ROR icon Autonomous University of Baja California
  • 38. ROR icon University of Siena
  • 39. ROR icon Osaka Kyoiku University
  • 40. ROR icon University of Chile
  • 41. ROR icon Special Astrophysical Observatory
  • 42. Institut de Radioastronomie Milimétrique, Avenida Divina Pastora 7, Local 20, 18012, Granada, Spain
  • 43. ROR icon Moscow Institute of Physics and Technology
  • 44. ROR icon University of Concepción
  • 45. ROR icon American Association of Variable Star Observers
  • 46. ROR icon Saint Mary's University
  • 47. ROR icon Abbey Ridge Observatory
  • 48. ROR icon Pulkovo Observatory
  • 49. National Sun Yat-sun University, 70 Lienhai Rd., Kaohsiung, 80424, Taiwan
  • 50. ROR icon Florida International University

Abstract

Context. Blazars are beamed active galactic nuclei (AGNs) known for their strong multi-wavelength variability on timescales ranging from years down to minutes. Many different models have been proposed to explain this variability. Aims. We aim to investigate the suitability of the twisting jet model presented in previous works to explain the multi-wavelength behaviour of BL Lacertae, the prototype of one of the blazar classes. According to this model, the jet is inhomogeneous, curved, and twisting, and the long-term variability is due to changes in the Doppler factor due to variations in the orientation of the jet-emitting regions. Methods. We analysed optical data of the source obtained during monitoring campaigns organised by the Whole Earth Blazar Telescope (WEBT) in 2019–2022, together with radio data from the WEBT and other teams, and γ-ray data from the Fermi satellite. In this period, BL Lacertae underwent an extraordinary activity phase, reaching its historical optical and γ-ray brightness maxima. Results. The application of the twisting jet model to the source light curves allows us to infer the wiggling motion of the optical, radio, and γ-ray jet-emitting regions. The optical-radio correlation shows that the changes in the radio viewing angle follow those in the optical viewing angle by about 120 days, and it suggests that the jet is composed of plasma filaments, which is in agreement with some radio high-resolution observations of other sources. The γ-ray emitting region is found to be co-spatial with the optical one, and the analysis of the γ-optical correlation is consistent with both the geometric interpretation and a synchrotron self-Compton (SSC) origin of the high-energy photons. Conclusions. We propose a geometric scenario where the jet is made up of a pair of emitting plasma filaments in a sort of double-helix curved rotating structure, whose wiggling motion produces changes in the Doppler beaming and can thus explain the observed multi-wavelength long-term variability.

Copyright and License

© The Authors 2024.

Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Acknowledgement

We thank Eduardo Ros (Max-Planck-Institut für Radioastronomie, Bonn, Germany) for insightful comments on the original version of the manuscript. We are grateful to M. L. Lister, to E. Egron, D. Perrodin, and M. Pili (INAF, Osservatorio Astronomico di Cagliari, Italy), to D. Lane (Burke-Gaffney and Abbey Ridge observatories, Canada), to N. A. Nizhelsky, G. V. Zhekanis, P. G. Tsybulev, and A. K. Erkenov (Special Astrophysical Observatory of RAS, Russia), to W. J. Hou, C. S. Lin, and H. Y. Hsiao (National Central University, Taiwan), and to L. Tilke and C. Singh (Connecticut College, USA) for support to the observations. We are indebted to Simona Villata and Giorgio Mogli for their help with the jet model graphics. This research has made use of NASA’s Astrophysics Data System Bibliographic Services and of the NASA/IPAC Extragalactic Database, which is funded by the National Aeronautics and Space Administration and operated by the California Institute of Technology. The INAF-OATo team acknowledges financial support from the INAF Fundamental Research Funding Call 2023. This research has made use of data from the OVRO 40-m monitoring program (Richards et al. 2011), supported by private funding from the California Insitute of Technology and the Max Planck Institute for Radio Astronomy, and by NASA grants NNX08AW31G, NNX11A043G, and NNX14AQ89G and NSF grants AST-0808050 and AST-1109911. This research has made use of data from the MOJAVE database that is maintained by the MOJAVE team Lister et al. (2018). The Medicina radio telescope is funded by the Ministry of University and Research (MUR) and is operated as National Facility by the National Institute for Astrophysics (INAF). The Sardinia Radio Telescope is funded by the Ministry of University and Research (MUR), Italian Space Agency (ASI), and the Autonomous Region of Sardinia (RAS) and is operated as National Facility by the National Institute for Astrophysics (INAF). The research at Boston University was supported by National Science Foundation grant AST-2108622 and NASA Fermi Guest Investigator grants 80NSSC22K1571 and 80NSSC23K1507. This study used observations conducted with the 1.8 m Perkins Telescope Observatory (PTO) in Arizona (USA), which is owned and operated by Boston University. The IAA-CSIC group acknowledges financial support from the grant CEX2021-001131-S funded by MCIN/AEI/10.13039/501100011033 to the Instituto de Astrofísica de Andalucía-CSIC. The IAA-CSIC activities were also supported by MICIN through grants PID2019-107847RB-C44 and PID2022-139117NB-C44. The POLAMI observations were carried out at the IRAM 30 m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). Some of the data are based on observations collected at the Centro Astronómico Hispano en Andalucía (CAHA), operated jointly by Junta de Andalucía and IAA-CSIC. Some of the data are based on observations collected at the Observatorio de Sierra Nevada, owned and operated by the IAA-CSIC. This paper is partly based on observations made with the IAC-80 telescope operated on the island of Tenerife by the Instituto de Astrofísica de Canarias in the Spanish Observatorio del Teide and on observations made with the LCOGT 0.4 m telescope network, one of whose nodes is located in the Spanish Observatorio del Teide. NRIAG team acknowledges financial support from the Egyptian Science, Technology & Innovation Funding Authority (STDF) under grant number 45779. We acknowledge support by Bulgarian National Science Fund under grant DN18-10/2017 and Bulgarian National Roadmap for Research Infrastructure Project D01-326/04.12.2023 of the Ministry of Education and Science of the Republic of Bulgaria. The R-band photometric data from the University of Athens Observatory (UOAO) were obtained in the frame of BOSS Project, after utilizing the robotic and remotely controlled instruments at the University of Athens (Gazeas 2016). This research was partially supported by the Bulgarian National Science Fund of the Ministry of Education and Science under grants KP-06-H38/4 (2019) and KP-06-H68/4 (2022). The Skinakas Observatory is a collaborative project of the University of Crete, the Foundation for Research and Technology – Hellas, and the Max-Planck-Institut für Extraterrestrische Physik. The work by Y.V.S., T.V.M., Y.A.K., A.V.P. is supported by the Ministry of Science and Higher Education of the Russian Federation under the contract 075-15-2024-541. M.D.J. thanks the Brigham Young University Department of Physics and Astronomy for continued support of the ongoing extragalactic monitoring program at the West Mountain Observatory. This work is partly based on observations carried out at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir (OAN-SPM), Baja California, Mexico. E.B. acknowledges support from DGAPA-UNAM grant IN113320. K.M. acknowledges support from JSPS KAKENHI grant number 19K03930. ACG’s work is partially supported by the CAS “Light of West China” Program (No. 2021-XBQNXZ-005) and the Xinjiang Tianshan Talents Program. G.D., O.V., M.D.J. and M.S. acknowledge support by the Astronomical Station Vidojevica and the Ministry of Science, Technological Development and Innovation of the Republic of Serbia (MSTDIRS) through contract no. 451-03-66/2024-03/200002 made with Astronomical Observatory (Belgrade), by the EC through project BELISSIMA (call FP7-REGPOT-2010-5, No. 256772), the observing and financial grant support from the Institute of Astronomy and Rozhen NAO BAS through the bilateral SANU-BAN joint research project “GAIA astrometry and fast variable astronomical objects”, and support by the SANU project F-187. Y.Y.K. was supported by the M2FINDERS project which has received funding from the European Research Council (ERC) under the European Union’s Horizon2020 Research and Innovation Programme (grant agreement No. 101018682). 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. We recognize that Maunakea is a culturally important site for the indigenous Hawaiian people; we are privileged to study the cosmos from its summit. Based on observations obtained with the SARA Observatory 0.9 m telescope at Kitt Peak, which is owned and operated by the Southeastern Association for Research in Astronomy (https://www.saraobservatory.org). The authors are honored to be permitted to conduct astronomical research on Iolkam Du’ag (Kitt Peak), a mountain with particular significance to the Tohono O’odham Nation. Fermi/LAT data were analysed with the Fermitools software (https://fermi.gsfc.nasa.gov/ssc/data/analysis/documentation/). Wavelet software was provided by C. Torrence and G. Compo, and is available at URL: http://paos.colorado.edu/research/wavelets/. Light curve simulations were based on the S. D. Connolly python version of the algorithm in ref. Emmanoulopoulos et al. (2013), which is available at https://github.com/samconnolly/DELightcurveSimulationConnolly (2015).

Data Availability

Data acquired by the WEBT Collaboration are stored in the WEBT archive and are available upon request to the WEBT President Massimo Villata (massimo.villata@inaf.it). Fermi/LAT data can be downloaded from the National Aeronautics and Space Administration (NASA) site (https://fermi.gsfc.nasa.gov/ssc/data/access/); the γ-ray light curve published here can be obtained from the authors upon request.

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Additional details

Related works

Is new version of
Discussion Paper: arXiv:2410.22319 (arXiv)

Funding

California Institute of Technology
Max Planck Institute for Radio Astronomy
National Aeronautics and Space Administration
NNX08AW31G
National Aeronautics and Space Administration
NNX11A043G
National Aeronautics and Space Administration
NNX14AQ89G
National Science Foundation
AST-0808050
National Science Foundation
AST-1109911
National Science Foundation
AST-2108622
National Aeronautics and Space Administration
80NSSC22K1571
National Aeronautics and Space Administration
80NSSC23K1507
Ministerio de Ciencia, Innovación y Universidades
CEX2021-001131-S
Instituto de Astrofísica de Andalucía
Ministerio de Ciencia, Innovación y Universidades
PID2019-107847RB-C44
Ministerio de Ciencia, Innovación y Universidades
PID2022-139117NB-C44
Science and Technology Development Fund
45779
Bulgarian Science Fund
DN18-10/2017
Ministry of Education and Science
D01-326/04.12.2023
Bulgarian Science Fund
KP-06-H38/4
Bulgarian Science Fund
KP-06-H68/4
The Ministry of Education and Science of the Russian Federation
075-15-2024-541
Universidad Nacional Autónoma de México
IN113320
Japan Society for the Promotion of Science
19K03930
Chinese Academy of Sciences
2021-XBQNXZ-005
Astronomical Observatory
Ministry of Education, Science and Technological Development
451-03-66/2024-03/200002
European Commission
256772
European Union
101018682
Smithsonian Institution
Academia Sinica

Dates

Accepted
2024-10-18
Available
2024-12-02
Published online

Caltech Custom Metadata

Caltech groups
Astronomy Department, Owens Valley Radio Observatory, Division of Physics, Mathematics and Astronomy (PMA)
Publication Status
Published