The WEBT Campaign on the Blazar 3C 279 in 2006
M. BöttcherDepartment of Physics and Astronomy, Astrophysical Institute, Clippinger 339, Ohio University, Athens, OH 45701Sarbani BasuDepartment of Physics and Astronomy, Astrophysical Institute, Clippinger 339, Ohio University, Athens, OH 45701M. JoshiDepartment of Physics and Astronomy, Astrophysical Institute, Clippinger 339, Ohio University, Athens, OH 45701M. VillataIstituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Torino, Via Osservatorio 20, I-10025 Pino Torinese, ItalyAkira AraiAstronomical Institute, Osaka Kyoiku University, Kashiwara-shi, Osaka 582-8582, JapanN. S. AryanDepartment of Physics, University of Colorado at Denver, Campus Box 157, P. O. Box 173364, Denver, CO 80217-3364I. M. AsfandiyarovUlugh Beg Astronomical Institute, Academy of Sciences of Uzbekistan, 33 Astronomical Str., Tashkent 700052, UzbekistanU. BachIstituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Torino, Via Osservatorio 20, I-10025 Pino Torinese, ItalyR. BachevInstitute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko Shosse Boulevard, 1784 Sofia, BulgariaA. BerduyginTuorla Observatory, University of Turku, 21500 Piikkiö, FinlandM. BlaekAstronomical Institute, Academy of Sciences of the Czech Republic, CZ-251 65 Ondrejov, Czech RepublicC. S. BuemiOsservatorio Astrofisico di Catania, Viale A. Doria 6, I-95125 Catania, ItalyA. J. Castro‐TiradoInstituto de Astrofisica de Andalucia, Apartado de Correos, 3004, E-18080 Granada, SpainA. de Ugarte PostigoInstituto de Astrofisica de Andalucia, Apartado de Correos, 3004, E-18080 Granada, SpainA. FrascaOsservatorio Astrofisico di Catania, Viale A. Doria 6, I-95125 Catania, ItalyL. FuhrmannIstituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Torino, Via Osservatorio 20, I-10025 Pino Torinese, ItalyV. A. Hagen‐ThornAstronomical Institute, St. Petersburg State University, Universitetsky pr. 28, Petrodvoretz, 198504 St. Petersburg, RussiaG. D. HensonDepartment of Physics, Astronomy, and Geology, East Tennessee State University and SARA Observatory, Box 70652, Johnson City, TN 37614T. HovattaMetsähovi Radio Observatory, Helsinki University of Technology, Metsähovintie 114, 02540 Kylmälä, FinlandR. HudecAstronomical Institute, Academy of Sciences of the Czech Republic, CZ-251 65 Ondrejov, Czech RepublicM. IbrahimovUlugh Beg Astronomical Institute, Academy of Sciences of Uzbekistan, 33 Astronomical Str., Tashkent 700052, UzbekistanYuko IshiiAstronomical Institute, Osaka Kyoiku University, Kashiwara-shi, Osaka 582-8582, JapanR. Z. IvanidzeAbastumani Observatory, 383762 Abastumani, GeorgiaM. JelínekInstituto de Astrofisica de Andalucia, Apartado de Correos, 3004, E-18080 Granada, SpainM. KamadaAstronomical Institute, Osaka Kyoiku University, Kashiwara-shi, Osaka 582-8582, JapanB. KapanadzeAbastumani Observatory, 383762 Abastumani, GeorgiaM. KatsuuraAstronomical Institute, Osaka Kyoiku University, Kashiwara-shi, Osaka 582-8582, JapanD. KotakaAstronomical Institute, Osaka Kyoiku University, Kashiwara-shi, Osaka 582-8582, JapanY. Y. KovalevAstro Space Center of Lebedev Physical Institute, Profsoyuznaya 84/32, Moscow 117997, RussiaYu. A. KovalevAstro Space Center of Lebedev Physical Institute, Profsoyuznaya 84/32, Moscow 117997, RussiaP. KubánekAstronomical Institute, Academy of Sciences of the Czech Republic, CZ-251 65 Ondrejov, Czech RepublicM. KurosakiAstronomical Institute, Osaka Kyoiku University, Kashiwara-shi, Osaka 582-8582, JapanO. M. KurtanidzeAbastumani Observatory, 383762 Abastumani, GeorgiaA. LähteenmäkiMetsähovi Radio Observatory, Helsinki University of Technology, Metsähovintie 114, 02540 Kylmälä, FinlandL. LanteriIstituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Torino, Via Osservatorio 20, I-10025 Pino Torinese, ItalyV. M. LarionovAstronomical Institute, St. Petersburg State University, Universitetsky pr. 28, Petrodvoretz, 198504 St. Petersburg, RussiaL. V. LarionovaAstronomical Institute, St. Petersburg State University, Universitetsky pr. 28, Petrodvoretz, 198504 St. Petersburg, RussiaChung‐Uk LeeKorea Astronomy and Space Science Institute, 61-1 Whaam-Dong, Yuseong-Gu, Daejeon 305-348, KoreaP. LetoIstituto di Radioastronomia, Sezione di Noto, C. da Renna Bassa-Loc. Casa di Mezzo C. P. 141, I-96017 Noto, ItalyE. LindforsTuorla Observatory, University of Turku, 21500 Piikkiö, FinlandE. MarilliOsservatorio Astrofisico di Catania, Viale A. Doria 6, I-95125 Catania, ItalyKevin MarshallDepartment of Physics and Astronomy, Georgia State University, Atlanta, GA 30303H. R. MillerDepartment of Physics and Astronomy, Georgia State University, Atlanta, GA 30303М. Г. МингалиевSpecial Astrophysical Observatory, Nizhnij Arkhyz, Karachai-Cherkessia 369167, RussiaN. MirabalDepartment of Astronomy, University of Michigan, 830 Dennison Building, Ann Arbor, MI 48109-1090S. MizoguchiAstronomical Institute, Osaka Kyoiku University, Kashiwara-shi, Osaka 582-8582, JapanK. NakamuraAstronomical Institute, Osaka Kyoiku University, Kashiwara-shi, Osaka 582-8582, JapanE. NieppolaMetsähovi Radio Observatory, Helsinki University of Technology, Metsähovintie 114, 02540 Kylmälä, FinlandM. G. NikolashviliAbastumani Observatory, 383762 Abastumani, GeorgiaK. NilssonTuorla Observatory, University of Turku, 21500 Piikkiö, FinlandShogo NishiyamaAstronomical Institute, Osaka Kyoiku University, Kashiwara-shi, Osaka 582-8582, JapanJ. OhlertM. A. OstermanDepartment of Physics and Astronomy, Georgia State University, Atlanta, GA 30303Soojong PakDepartment of Astronomy and Space Science, Kyung Hee University, Seocheon, Gilheung, Yongin, Gyeonggi, 446-701, South KoreaM. PasanenTuorla Observatory, University of Turku, 21500 Piikkiö, FinlandC. S. PetersDepartment of Physics and Astronomy, Dartmouth College, MS 6127, Hannover, NH 03755T. PursimoNordic Optical Telescope, Apartado 474, E-38700 Santa Cruz de La Palma, Santa Cruz de Tenerife, SpainC. M. RaiteriIstituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Torino, Via Osservatorio 20, I-10025 Pino Torinese, ItalyJacob RobertsonFlorida Institute of Technology and SARA Observatory, 150 West University Boulevard, Melbourne, FL 32901-6975T. H. RobertsonBall State University and SARA Observatory, Department of Physics and Astronomy, Munice, IN 47306W. T. RyleDepartment of Physics and Astronomy, Georgia State University, Atlanta, GA 30303Kunihiko SadakaneAstronomical Institute, Osaka Kyoiku University, Kashiwara-shi, Osaka 582-8582, JapanA. C. SadunDepartment of Physics, University of Colorado at Denver, Campus Box 157, P. O. Box 173364, Denver, CO 80217-3364L. A. SiguaAbastumani Observatory, 383762 Abastumani, GeorgiaBong Won SohnKorea Astronomy and Space Science Institute, 61-1 Whaam-Dong, Yuseong-Gu, Daejeon 305-348, KoreaA. StrigachevInstitute of Astronomy, Bulgarian Academy of Sciences, 72 Tsarigradsko Shosse Boulevard, 1784 Sofia, BulgariaN. SumitomoAstronomical Institute, Osaka Kyoiku University, Kashiwara-shi, Osaka 582-8582, JapanL. O. TakaloTuorla Observatory, University of Turku, 21500 Piikkiö, FinlandY. TamesueAstronomical Institute, Osaka Kyoiku University, Kashiwara-shi, Osaka 582-8582, JapanK. TanakaAstronomical Institute, Osaka Kyoiku University, Kashiwara-shi, Osaka 582-8582, JapanJ. R. ThorstensenDepartment of Physics and Astronomy, Dartmouth College, MS 6127, Hannover, NH 03755G. TostiOsservatorio Astronomico, Università di Perugia, Via B. Bonfigli, I-06126 Perugia, ItalyC. TrigilioOsservatorio Astrofisico di Catania, Viale A. Doria 6, I-95125 Catania, ItalyG. UmanaOsservatorio Astrofisico di Catania, Viale A. Doria 6, I-95125 Catania, ItalyS. VennesFlorida Institute of Technology and SARA Observatory, 150 West University Boulevard, Melbourne, FL 32901-6975S. VítekInstituto de Astrofisica de Andalucia, Apartado de Correos, 3004, E-18080 Granada, SpainA. E. VolvachCrimean Astrophysical Observatory, Nauchny, Crimea 98409, UkraineJ. R. WebbFlorida International University and SARA Observatory, University Park Campus, Miami, FL 33199M. YamanakaAstronomical Institute, Osaka Kyoiku University, Kashiwara-shi, Osaka 582-8582, JapanHong-Suh YimAstronomical Institute, St. Petersburg State University, Universitetsky pr. 28, Petrodvoretz, 198504 St. Petersburg, Russia
ABI
Аннотация
The quasar 3C 279 was the target of an extensive multiwavelength monitoring campaign from 2006 January through April. An optical-IR-radio monitoring campaign by the Whole Earth Blazar Telescope (WEBT) collaboration was organized around target-of-opportunity X-ray and soft γ-ray observations with Chandra and INTEGRAL in 2006 mid-January, with additional X-ray coverage by RXTE and Swift XRT. In this paper we focus on the results of the WEBT campaign. The source exhibited substantial variability of optical flux and spectral shape, with a characteristic timescale of a few days. The variability patterns throughout the optical BVRI bands were very closely correlated with each other, while there was no obvious correlation between the optical and radio variability. After the ToO trigger, the optical flux underwent a remarkably clean quasi-exponential decay by about 1 mag, with a decay timescale of τd ~ 12.8 days. In intriguing contrast to other (in particular, BL Lac type) blazars, we find a lag of shorter wavelength behind longer wavelength variability throughout the RVB wavelength ranges, with a time delay increasing with increasing frequency. Spectral hardening during flares appears delayed with respect to a rising optical flux. This, in combination with the very steep IR-optical continuum spectral index of α0 ~ 1.5-2.0, may indicate a highly oblique magnetic field configuration near the base of the jet, leading to inefficient particle acceleration and a very steep electron injection spectrum. An alternative explanation through a slow (timescale of several days) acceleration mechanism would require an unusually low magnetic field of B lesssim 0.2 G, about an order of magnitude lower than inferred from previous analyses of simultaneous SEDs of 3C 279 and other flat-spectrum radio quasars with similar properties.
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