Fulltext

The WEBT campaign on the BL Lac object PG 1553+113 in 2013. An analysis of the enigmatic synchrotron emission

Raiteri, C. M. ; Stamerra, A. ; Villata, M. ; Larionov, V. M. ; Acosta-Pulido, J. A. ; Arévalo, M. J. ; Arkharov, A. A. ; Bachev, R. ; Benítez, E. ; Bozhilov, V. V. ; Borman, G. A. ; Buemi, C. S. ; Calcidese, P. ; Carnerero, M. I. ; Carosati, D. ; Chigladze, R. A. ; Damljanovic, G. ; Di Paola, A. ; Doroshenko, V. T. ; Efimova, N. V. ; Ehgamberdiev, Sh. A. ; Giroletti, M. ; González-Morales, P. A. ; Grinon-Marin, A. B. ; Grishina, T. S. ; Hiriart, D. ; Ibryamov, S. ; Klimanov, S. A. ; Kopatskaya, E. N. ; Kurtanidze, O. M. ; Kurtanidze, S. O. ; Kurtenkov, A. A. ; Larionova, L. V. ; Larionova, E. G. ; Lázaro, C. ; Lähteenmäki, A. ; Leto, P. ; Markovic, G. ; Mirzaqulov, D. O. ; Mokrushina, A. A. ; Morozova, D. A. ; Mújica, R. ; Nazarov, S. V. ; Nikolashvili, M. G. ; Ohlert, J. M. ; Ovcharov, E. P. ; Paiano, S. ; Pastor Yabar, A. ; Prandini, E. ; Ramakrishnan, V. ; Sadun, A. C. ; Semkov, E. ; Sigua, L. A. ; Strigachev, A. ; Tammi, J. ; Tornikoski, M. ; Trigilio, C. ; Troitskaya, Yu. V. ; Troitsky, I. S. ; Umana, G. ; Velasco, S. ; Vince, O.

In: Monthly Notices of the Royal Astronomical Society, 2015, vol. 454, no. 1, p. 353-367

Add to personal list
    Title
    • The WEBT campaign on the BL Lac object PG 1553+113 in 2013. An analysis of the enigmatic synchrotron emission
    Author
    • Raiteri, C. M.. INAF, Osservatorio Astrofisico di Torino, via Osservatorio 20, I-10025 Pino Torinese, Italy
    • Stamerra, A.. INAF, Osservatorio Astrofisico di Torino, via Osservatorio 20, I-10025 Pino Torinese, Italy
    • Villata, M.. INAF, Osservatorio Astrofisico di Torino, via Osservatorio 20, I-10025 Pino Torinese, Italy
    • Larionov, V. M.. Astronomical Institute, St Petersburg State University, 198504 St Petersburg, Russia
    • Acosta-Pulido, J. A.. Instituto de Astrofisica de Canarias (IAC), La Laguna, E-38200 Tenerife, Spain
    • Arévalo, M. J.. Instituto de Astrofisica de Canarias (IAC), La Laguna, E-38200 Tenerife, Spain
    • Arkharov, A. A.. Pulkovo Observatory, 196140 St Petersburg, Russia
    • Bachev, R.. Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko shosse Blvd, 1784 Sofia, Bulgaria
    • Benítez, E.. Instituto de Astronomía, Universidad Nacional Autónoma de México, 04510 Mexico DF, Mexico
    • Bozhilov, V. V.. Department of Astronomy, University of Sofia "St. Kliment Ohridski”, BG-1164 Sofia, Bulgaria
    • Borman, G. A.. Crimean Astrophysical Observatory, P/O Nauchny, 298409 Crimea
    • Buemi, C. S.. INAF, Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95123 Catania, Italy
    • Calcidese, P.. Osservatorio Astronomico della Regione Autonoma Valle d'Aosta, Saint-Barthélemy, I-11020 Nus, Italy
    • Carnerero, M. I.. INAF, Osservatorio Astrofisico di Torino, via Osservatorio 20, I-10025 Pino Torinese, Italy
    • Carosati, D.. EPT Observatories, Tijarafe, E-38780 La Palma, Spain
    • Chigladze, R. A.. Abastumani Observatory, Mt Kanobili, 0301 Abastumani, Georgia
    • Damljanovic, G.. Astronomical Observatory, Volgina 7, 11060 Belgrade, Serbia
    • Di Paola, A.. INAF, Osservatorio Astronomico di Roma, I-00040 Monte Porzio Catone, Italy
    • Doroshenko, V. T.. Southern Station of the Sternberg Astronomical Institute, Moscow M.V. Lomonosov State University, P/O Nauchny, 298409 Crimea
    • Efimova, N. V.. Pulkovo Observatory, 196140 St Petersburg, Russia
    • Ehgamberdiev, Sh. A.. Ulugh Beg Astronomical Institute, Maidanak Observatory, Uzbekistan
    • Giroletti, M.. INAF, Istituto di Radioastronomia, via Gobetti 101, I-40129 Bologna, Italy
    • González-Morales, P. A.. Instituto de Astrofisica de Canarias (IAC), La Laguna, E-38200 Tenerife, Spain
    • Grinon-Marin, A. B.. Instituto de Astrofisica de Canarias (IAC), La Laguna, E-38200 Tenerife, Spain
    • Grishina, T. S.. Astronomical Institute, St Petersburg State University, 198504 St Petersburg, Russia
    • Hiriart, D.. Instituto de Astronomía, Universidad Nacional Autónoma de México, 22800 Ensenada, BC, Mexico
    • Ibryamov, S.. Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko shosse Blvd, 1784 Sofia, Bulgaria
    • Klimanov, S. A.. Pulkovo Observatory, 196140 St Petersburg, Russia
    • Kopatskaya, E. N.. Astronomical Institute, St Petersburg State University, 198504 St Petersburg, Russia
    • Kurtanidze, O. M.. Abastumani Observatory, Mt Kanobili, 0301 Abastumani, Georgia
    • Kurtanidze, S. O.. Abastumani Observatory, Mt Kanobili, 0301 Abastumani, Georgia
    • Kurtenkov, A. A.. Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko shosse Blvd, 1784 Sofia, Bulgaria
    • Larionova, L. V.. Astronomical Institute, St Petersburg State University, 198504 St Petersburg, Russia
    • Larionova, E. G.. Astronomical Institute, St Petersburg State University, 198504 St Petersburg, Russia
    • Lázaro, C.. Instituto de Astrofisica de Canarias (IAC), La Laguna, E-38200 Tenerife, Spain
    • Lähteenmäki, A.. Aalto University Metsähovi Radio Observatory, Metsähovintie 114, FI-02540 Kylmälä, Finland
    • Leto, P.. INAF, Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95123 Catania, Italy
    • Markovic, G.. Faculty of Mathematics, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia
    • Mirzaqulov, D. O.. Ulugh Beg Astronomical Institute, Maidanak Observatory, Uzbekistan
    • Mokrushina, A. A.. Astronomical Institute, St Petersburg State University, 198504 St Petersburg, Russia
    • Morozova, D. A.. Astronomical Institute, St Petersburg State University, 198504 St Petersburg, Russia
    • Mújica, R.. Instituto Nacional de Astrofísica, Óptica y Electrónica, 72840 Puebla, Mexico
    • Nazarov, S. V.. Crimean Astrophysical Observatory, P/O Nauchny, 298409 Crimea
    • Nikolashvili, M. G.. Abastumani Observatory, Mt Kanobili, 0301 Abastumani, Georgia
    • Ohlert, J. M.. Michael Adrian Observatory, Fichtenstrasse 7, D-65468 Trebur, Germany
    • Ovcharov, E. P.. Department of Astronomy, University of Sofia "St. Kliment Ohridski”, BG-1164 Sofia, Bulgaria
    • Paiano, S.. INFN, I-35131 Padova, Italy
    • Pastor Yabar, A.. Instituto de Astrofisica de Canarias (IAC), La Laguna, E-38200 Tenerife, Spain
    • Prandini, E.. ETH Zurich, CH-8093 Zurich, Switzerland
    • Ramakrishnan, V.. Aalto University Metsähovi Radio Observatory, Metsähovintie 114, FI-02540 Kylmälä, Finland
    • Sadun, A. C.. Department of Physics, University of Colorado Denver, CO, 80217-3364 USA
    • Semkov, E.. Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko shosse Blvd, 1784 Sofia, Bulgaria
    • Sigua, L. A.. Abastumani Observatory, Mt Kanobili, 0301 Abastumani, Georgia
    • Strigachev, A.. Institute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko shosse Blvd, 1784 Sofia, Bulgaria
    • Tammi, J.. Aalto University Metsähovi Radio Observatory, Metsähovintie 114, FI-02540 Kylmälä, Finland
    • Tornikoski, M.. Aalto University Metsähovi Radio Observatory, Metsähovintie 114, FI-02540 Kylmälä, Finland
    • Trigilio, C.. INAF, Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95123 Catania, Italy
    • Troitskaya, Yu. V.. Astronomical Institute, St Petersburg State University, 198504 St Petersburg, Russia
    • Troitsky, I. S.. Astronomical Institute, St Petersburg State University, 198504 St Petersburg, Russia
    • Umana, G.. INAF, Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95123 Catania, Italy
    • Velasco, S.. Instituto de Astrofisica de Canarias (IAC), La Laguna, E-38200 Tenerife, Spain
    • Vince, O.. Astronomical Observatory, Volgina 7, 11060 Belgrade, Serbia
    Document Type
    • Postprint
    Language
    • English
    Published in
    • Monthly Notices of the Royal Astronomical Society, 2015, vol. 454, no. 1, p. 353-367. Oxford University Press
    Other Version
    OAI-PMH Identifier
    • oai:doc.rero.ch:300778
    Summary
    A multifrequency campaign on the BL Lac object PG 1553+113 was organized by the Whole Earth Blazar Telescope (WEBT) in 2013 April-August, involving 19 optical, two near-IR, and three radio telescopes. The aim was to study the source behaviour at low energies during and around the high-energy observations by the Major Atmospheric Gamma-ray Imaging Cherenkov telescopes in April-July. We also analyse the UV and X-ray data acquired by the Swift and XMM-Newton satellites in the same period. The WEBT and satellite observations allow us to detail the synchrotron emission bump in the source spectral energy distribution (SED). In the optical, we found a general bluer-when-brighter trend. The X-ray spectrum remained stable during 2013, but a comparison with previous observations suggests that it becomes harder when the X-ray flux increases. The long XMM-Newton exposure reveals a curved X-ray spectrum. In the SED, the XMM-Newton data show a hard near-UV spectrum, while Swift data display a softer shape that is confirmed by previous Hubble Space Telescope/Cosmic Origins Spectrograph and International Ultraviolet Explorer observations. Polynomial fits to the optical-X-ray SED show that the synchrotron peak likely lies in the 4-30eV energy range, with a general shift towards higher frequencies for increasing X-ray brightness. However, the UV and X-ray spectra do not connect smoothly. Possible interpretations include: (i) orientation effects, (ii) additional absorption, (iii) multiple emission components, and (iv) a peculiar energy distribution of relativistic electrons. We discuss the first possibility in terms of an inhomogeneous helical jet model