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WEBT multiwavelength monitoring and XMM-Newton observations of BL Lacertae in 2007-2008. Unveiling different emission components

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.
dc.contributor.authorCAPETTI, A.
hal.structure.identifierInstituto de Neurociencias de Alicante
dc.contributor.authorALLER, M. F.
dc.contributor.authorBACH, U.
dc.contributor.authorCALCIDESE, P.
dc.contributor.authorGURWELL, M. A.
dc.contributor.authorLARIONOV, V. M.
dc.contributor.authorOHLERT, J.
dc.contributor.authorNILSSON, K.
dc.contributor.authorSTRIGACHEV, 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.created2009-09-09
dc.date.issued2009
dc.identifier.issn0004-6361
dc.description.abstractEnIn 2007-2008 we carried out a new multiwavelength campaign of the Whole Earth Blazar Telescope (WEBT) on BL Lacertae, involving three pointings by the XMM-Newton satellite, to study its emission properties. The source was monitored in the optical-to-radio bands by 37 telescopes. The brightness level was relatively low. Some episodes of very fast variability were detected in the optical bands. The X-ray spectra are well fitted by a power law with photon index of about 2 and photoelectric absorption exceeding the Galactic value. However, when taking into account the presence of a molecular cloud on the line of sight, the data are best fitted by a double power law, implying a concave X-ray spectrum. The spectral energy distributions (SEDs) built with simultaneous radio-to-X-ray data at the epochs of the XMM-Newton observations suggest that the peak of the synchrotron emission lies in the near-IR band, and show a prominent UV excess, besides a slight soft-X-ray excess. A comparison with the SEDs corresponding to previous observations with X-ray satellites shows that the X-ray spectrum is extremely variable. We ascribe the UV excess to thermal emission from the accretion disc, and the other broad-band spectral features to the presence of two synchrotron components, with their related SSC emission. We fit the thermal emission with a black body law and the non-thermal components by means of a helical jet model. The fit indicates a disc temperature greater than 20000 K and a luminosity greater than 6 x 10^44 erg/s.
dc.language.isoen
dc.publisherEDP Sciences
dc.title.enWEBT multiwavelength monitoring and XMM-Newton observations of BL Lacertae in 2007-2008. Unveiling different emission components
dc.typeArticle de revue
dc.subject.halPhysique [physics]/Astrophysique [astro-ph]/Phénomènes cosmiques de haute energie [astro-ph.HE]
dc.subject.halPlanète et Univers [physics]/Astrophysique [astro-ph]/Phénomènes cosmiques de haute energie [astro-ph.HE]
dc.identifier.arxiv0909.1701
bordeaux.journalAstronomy and Astrophysics - A&A
bordeaux.page769-779
bordeaux.volume507
bordeaux.peerReviewedoui
hal.identifierhal-00426682
hal.version1
hal.popularnon
hal.audienceNon spécifiée
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-00426682v1
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