Another look at the BL Lacertae flux and spectral variability:Observations by GASP-WEBT, XMM- Newton, and Swift in 2008-2009
C. M. Raiteri,M. Villata,L. Bruschini,Alessandro Capetti,Omar M. Kurtanidze,Valeri M. Larionov,Valeri M. Larionov,P. Romano,S. Vercellone,I. Agudo,I. Agudo,Hugh D. Aller,M. F. Aller,A. A. Arkharov,U. Bach,Andrei Berdyugin,Dmitry A. Blinov,Markus Böttcher,Carla Buemi,P. Calcidese,D. Carosati,Ricard Casas,Wen Ping Chen,J. M. Coloma,C. Diltz,A. Di Paola,Mauro Dolci,N. V. Efimova,E. Forné,José L. Gómez,Mark Gurwell,Antti Hakola,Talvikki Hovatta,Talvikki Hovatta,H. Y. Hsiao,B. Jordan,S. G. Jorstad,Ekaterina Koptelova,Sofia O. Kurtanidze,Anne Lähteenmäki,Elena G. Larionova,Paolo Leto,Elina Lindfors,R. Ligustri,Alan P. Marscher,D. A. Morozova,M. G. Nikolashvili,Kari Nilsson,J. A. Ros,P. Roustazadeh,A. C. Sadun,A. Sillanpää,J. Sainio,L. O. Takalo,Merja Tornikoski,Corrado Trigilio,Ivan S. Troitsky,G. Umana +57 more
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In this paper, the authors investigated the role of the helical jet model in the broad-band emission and variability properties of BL Lacertae, and showed that the jet geometry can play an extremely important role in the source's flux and spectral v ariability.Abstract:
Aims. In a previous study we suggested that the broad-band emission and variability properties of BL Lacertae can be accounted for by a double synchrotron emission component with related inverse-Compton emission from the jet, plus thermal radiation from the accretion disc. Here we investigate the matter with further data extending over a wider energy range. Methods. The GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) monitored BL Lacertae in 2008‐2009 at radio, near-IR, and optical frequencies to follow its flux behaviour. During this period, high-energy observations were performed by XMMNewton, Swift, and Fermi. We analyse these data with particular attention to the calibration of Swift UV data, and apply a helical jet model to interpret the source broad-band variability. Results. The GASP-WEBT observations show an optical flare in 2008 February‐March, and oscillations of several tenths of mag on a few-day time scale afterwards. The radio flux is only mildly variable . The UV data from both XMM-Newton and Swift seem to confirm a UV excess that is likely caused by thermal emission from the accretion disc. The X-ray data from XMM-Newton indicate a strongly concave spectrum, as well as moderate (�4‐7%) flux variability on an hour time scale. The Swift X-ray d ata reveal fast (interday) flux changes, not correlated with those observed at lower energies. We compare the spectral energy distribution (SED) corresponding to the 2008 low-brightness state, which was characterised by a synchrotron dominance, to the 1997 outburst state, where the inverse-Compton emission was prevailing. A fit with an inhomogeneous helical jet model suggests that two synchrotron components are at work with their self inverse-Compton emission. Most likely, they represent the radiation from two distinct emitting reg ions in the jet. We show that the difference between the source SEDs in 2008 and 1997 can be explained in terms of pure geometrical variations. The outburst state occurred when the jet-emitting regions were better aligned with the line of sight, producing an increase of the Doppler beaming factor. Conclusions. Our analysis demonstrates that the jet geometry can play an extremely important role in the BL Lacertae flux and spectral v ariability. Indeed, the emitting jet is probably a bent and dynamic structure, and hence changes in the emitting regions viewing angles are likely to happen, with strong consequences on the source multiwavelength behaviour.read more
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Journal ArticleDOI
SBS 0846+513: a new γ-ray-emitting narrow-line Seyfert 1 galaxy
Filippo D'Ammando,Filippo D'Ammando,M. Orienti,M. Orienti,Justin D. Finke,C. M. Raiteri,E. Angelakis,Lars Fuhrmann,Marcello Giroletti,Talvikki Hovatta,Walter Max-Moerbeck,J. S. Perkins,J. S. Perkins,Anthony C. S. Readhead,J. L. Richards,Łukasz Stawarz,Davide Donato,Davide Donato +17 more
TL;DR: In this paper, the radio-loud active galactic nucleus SBS 0846+513 (z = 0.5835), optically classified as a narrow-line Seyfert 1 galaxy, together with new and archival radio-to-X-ray data were reported.
Journal ArticleDOI
SBS 0846+513: a new gamma-ray emitting Narrow-Line Seyfert 1 galaxy
Filippo D'Ammando,M. Orienti,Justin D. Finke,C. M. Raiteri,Emmanouil Angelakis,L. Fuhrmann,Marcello Giroletti,Talvikki Hovatta,Walter Max-Moerbeck,J. S. Perkins,A. C. S. Readhead,J. L. Richards,L. Stawarz,D. Donato +13 more
TL;DR: In this paper, Fermi-LAT observations of the radio-loud AGN SBS 0846+513 (z=0.5835), optically classified as a narrow-line Seyfert 1 galaxy, together with new and archival radio-to-X-ray data are reported.
Journal ArticleDOI
The awakening of BL Lacertae: observations by Fermi, Swift and the GASP-WEBT
C. M. Raiteri,M. Villata,Filippo D'Ammando,Filippo D'Ammando,Valeri M. Larionov,Valeri M. Larionov,Valeri M. Larionov,Mark Gurwell,D. O. Mirzaqulov,Paul S. Smith,J. A. Acosta-Pulido,J. A. Acosta-Pulido,Iván Agudo,Iván Agudo,M. J. Arévalo,M. J. Arévalo,Rumen Bachev,Erika Benítez,A. Berdyugin,Dmitry A. Blinov,Dmitry A. Blinov,G. A. Borman,Markus Böttcher,Markus Böttcher,V. Bozhilov,M. I. Carnerero,M. I. Carnerero,M. I. Carnerero,D. Carosati,Carolina Casadio,Wen Ping Chen,V. T. Doroshenko,Yu. S. Efimov,N. V. Efimova,N. V. Efimova,Sh. A. Ehgamberdiev,José L. Gómez,Pedro A. Gonzalez-Morales,David Hiriart,Sunay Ibryamov,Y. Jadhav,Svetlana G. Jorstad,Svetlana G. Jorstad,Manasvita Joshi,V. Kadenius,S. A. Klimanov,Meenakshi Kohli,Tatiana S. Konstantinova,E. N. Kopatskaya,Ekaterina Koptelova,Ekaterina Koptelova,Givi N. Kimeridze,Omar M. Kurtanidze,Elena G. Larionova,L. V. Larionova,R. Ligustri,Elina Lindfors,Alan P. Marscher,B. McBreen,I. M. McHardy,Y. Metodieva,Sol N. Molina,D. A. Morozova,S. V. Nazarov,M. G. Nikolashvili,Kari Nilsson,D. N. Okhmat,Evgeni Ovcharov,Neelam Panwar,M. Pasanen,Stoyanka Peneva,J. Phipps,N. G. Pulatova,R. Reinthal,J. A. Ros,A. C. Sadun,R. D. Schwartz,Evgeni Semkov,S. G. Sergeev,Lorand A. Sigua,A. Sillanpää,N. Smith,K. A. Stoyanov,A. Strigachev,L. O. Takalo,Brian W. Taylor,Brian W. Taylor,Clemens Thum,Ivan S. Troitsky,Antoniya Valcheva,Ann E. Wehrle,Helmut Wiesemeyer +91 more
TL;DR: In this article, the authors investigated the effects of a geometrical interpretation of the long-term flux variability on the polarization of BL Lacertae and found that the mean optical degree of polarization slightly decreases over the considered period and in general it is higher when the flux is lower.
Journal ArticleDOI
An optical view of BL Lacertae objects
TL;DR: In this article, the authors review the main observational facts that contribute to the present basic interpretation of active galaxies and present knowledge of the host galaxies, their environments, and central black hole masses.
Journal ArticleDOI
RAPID TeV GAMMA-RAY FLARING OF BL LACERTAE
T. Arlen,T. Aune,M. Beilicke,Wystan Benbow,A. Bouvier,J. H. Buckley,V. Bugaev,A. Cesarini,L. Ciupik,M. P. Connolly,Wei Cui,R. Dickherber,J. Dumm,Manel Errando,Abraham D. Falcone,S. Federici,Q. Feng,J. P. Finley,G. Finnegan,Lucy Fortson,A. Furniss,N. Galante,D. Gall,S. Griffin,J. Grube,Geza Gyuk,D. S. Hanna,Jamie Holder,T. B. Humensky,P. Kaaret,N. Karlsson,M. Kertzman,Y. Khassen,David Kieda,H. Krawczynski,F. Krennrich,Gernot Maier,P. Moriarty,R. Mukherjee,T. J. N. Nelson,A. O'Faolain de Bhroithe,R. A. Ong,M. Orr,N. H. Park,J. S. Perkins,J. S. Perkins,A. Pichel,Martin Pohl,H. Prokoph,John L. Quinn,K. Ragan,Luis C. Reyes,P. T. Reynolds,E. Roache,D. B. Saxon,M. Schroedter,G. H. Sembroski,D. Staszak,I. Telezhinsky,G. Tešić,M. Theiling,K. Tsurusaki,A. Varlotta,S. Vincent,S. P. Wakely,T. C. Weekes,A. Weinstein,R. Welsing,David A. Williams,B. Zitzer,Svetlana G. Jorstad,Svetlana G. Jorstad,Nicholas R. MacDonald,Alan P. Marscher,Paul S. Smith,R. C. Walker,Talvikki Hovatta,Joseph L. Richards,Walter Max-Moerbeck,Anthony C. S. Readhead,Matthew L. Lister,Yuri Y. Kovalev,Alexander B. Pushkarev,Mark Gurwell,Anne Lähteenmäki,E. Nieppola,Merja Tornikoski,Emilia Järvelä +87 more
TL;DR: A very rapid TeV gamma-ray flare from BL Lacertae was detected by the Very Energetic Radiation Imaging Telescope Array System (VERITAS) with a 34.6 minute exposure as discussed by the authors.
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