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The high activity of 3C 454.3 in autumn 2007. Monitoring by the WEBT during the AGILE detection

hal.structure.identifierINAF - Osservatorio Astrofisico di Torino [OATo]
dc.contributor.authorRAITERI, C. M.
hal.structure.identifierINAF - Osservatorio Astrofisico di Torino [OATo]
dc.contributor.authorVILLATA, M.
hal.structure.identifierLaboratoire de Physico-Chimie de l'Atmosphère [LPCA]
hal.structure.identifierLaboratoire de chimie bactérienne [LCB]
hal.structure.identifierFujian Institute of Research on the Structure of Matter
hal.structure.identifierInsitute of Geology China Earthquake Administration Beijing 100029, China (X.X., G.C., W.C.) [INSITUTE OF GEOLOGY]
hal.structure.identifierECE Dept.
hal.structure.identifierHarbin Institute of Technology [HIT]
hal.structure.identifierDepartment of Information Science and Media Studies [Bergen] [UiB]
hal.structure.identifierInstitute of Geology
hal.structure.identifierLinköping University [LIU]
hal.structure.identifierDepartment of Mechanical Engineering
hal.structure.identifierResearch Center for Environmental Changes
hal.structure.identifierInstitute of Earthquake Prediction Research
dc.contributor.authorCHEN, W. P.
dc.contributor.authorHSIAO, W. -S.
dc.contributor.authorKURTANIDZE, O. M.
dc.contributor.authorNILSSON, K.
dc.contributor.authorLARIONOV, V. M.
dc.contributor.authorGURWELL, M. A.
hal.structure.identifierLaboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
hal.structure.identifierObservatoire aquitain des sciences de l'univers [OASU]
hal.structure.identifierLaboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
dc.contributor.authorCHARLOT, P.
dc.date.created2008
dc.date.issued2008
dc.identifier.issn0004-6361
dc.description.abstractEnThe quasar-type blazar 3C 454.3 underwent a phase of high activity in summer and autumn 2007, which was intensively monitored in the radio-to-optical bands by the Whole Earth Blazar Telescope (WEBT). The gamma-ray satellite AGILE detected this source first in late July, and then in November-December 2007. In this letter we present the multifrequency data collected by the WEBT and collaborators during the second AGILE observing period, complemented by a few contemporaneous data from UVOT onboard the Swift satellite. The aim is to trace in detail the behaviour of the synchrotron emission from the blazar jet, and to investigate the contribution from the thermal emission component. Optical data from about twenty telescopes have been homogeneously calibrated and carefully assembled to construct an R-band light curve containing about 1340 data points in 42 days. This extremely well-sampled optical light curve allows us to follow the dramatic flux variability of the source in detail. In addition, we show radio-to-UV spectral energy distributions (SEDs) at different epochs, which represent different brightness levels. In the considered period, the source varied by 2.6 mag in a couple of weeks in the R band. Many episodes of fast (i.e. intranight) variability were observed, most notably on December 12, when a flux increase of about 1.1 mag in 1.5 hours was detected, followed by a steep decrease of about 1.2 mag in 1 hour. The contribution by the thermal component is difficult to assess, due to the uncertainties in the Galactic, and possibly also intrinsic, extinction in the UV band. However, polynomial fitting of radio-to-UV SEDs reveals an increasing spectral bending going towards fainter states, suggesting a UV excess likely due to the thermal emission from the accretion disc.
dc.language.isoen
dc.publisherEDP Sciences
dc.title.enThe high activity of 3C 454.3 in autumn 2007. Monitoring by the WEBT during the AGILE detection
dc.typeArticle de revue
dc.identifier.doi10.1051/0004-6361:200809995
dc.subject.halPhysique [physics]/Astrophysique [astro-ph]/Cosmologie et astrophysique extra-galactique [astro-ph.CO]
dc.subject.halPlanète et Univers [physics]/Astrophysique [astro-ph]
dc.identifier.arxiv0805.1983
bordeaux.journalAstronomy and Astrophysics - A&A
bordeaux.pageL17-L20
bordeaux.volume485
bordeaux.issue2
bordeaux.peerReviewedoui
hal.identifierhal-00299903
hal.version1
hal.popularnon
hal.audienceInternationale
dc.subject.esgalaxies: active
dc.subject.esgalaxies: quasars: general
dc.subject.esgalaxies: quasars: individual: 3C 454.3
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-00299903v1
bordeaux.COinSctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=Astronomy%20and%20Astrophysics%20-%20A&A&rft.date=2008&rft.volume=485&rft.issue=2&rft.spage=L17-L20&rft.epage=L17-L20&rft.eissn=0004-6361&rft.issn=0004-6361&rft.au=RAITERI,%20C.%20M.&VILLATA,%20M.&CHEN,%20W.%20P.&HSIAO,%20W.%20-S.&KURTANIDZE,%20O.%20M.&rft.genre=article


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