The blazarAO 0235+164 (z=0.94) has been one of the most active objects observed by Fermi Large Area Telescope (LAT) since its launch in Summer 2008. In addition to the continuous coverage by Fermi, contemporaneous observations were carried out from the radio to gamma-ray bands between 2008 September and 2009 February. In this paper, we summarize the rich multi-wavelength data collected during the campaign (including F-GAMMA, GASP-WEBT, Kanata, OVRO, RXTE, SMARTS, Swift, and other instruments), examine the cross-correlation between the light curves measured in the different energy bands, and interpret the resulting spectral energy distributions in the context of well-known blazar emission models. We find that the gamma-ray activity is well correlated with a series of near-IR/optical flares, accompanied by an increase in the optical polarization degree. On the other hand, the X-ray light curve shows a distinct 20 day high state of unusually soft spectrum, which does not match the extrapolation of the optical/UV synchrotron spectrum. We tentatively interpret this feature as the bulk Compton emission by cold electrons contained in the jet, which requires an accretion disk corona with an effective covering factor of 19% at a distance of 100 R-g. We model the broadband spectra with a leptonic model with external radiation dominated by the infrared emission from the dusty torus.
MULTI-WAVELENGTH OBSERVATIONS OF BLAZAR AO 0235+164 IN THE 2008-2009 FLARING STATE / Ackermann M; Ajello M; Ballet J; Barbiellini G; Bastieri D; Bellazzini R; Blandford RD; Bloom ED; Bonamente E; Borgland AW; Bottacini E; Bregeon J; Brigida M; Bruel P; Buehler R; Buson S; Caliandro GA; Cameron RA; Caraveo PA; Casandjian JM; Cavazzuti E; Cecchi C; Charles E; Chekhtman A; Chiang J; Ciprini S; Claus R; Cohen-Tanugi J; Cutini S; DAmmando F; de Palma F; Dermer CD; Silva EDE; Drell PS; Drlica-Wagner A; Dubois R; Favuzzi C; Fegan SJ; Ferrara EC; Focke WB; Fortin P; Fuhrmann L; Fukazawa Y; Fusco P; Gargano F; Gasparrini D; Gehrels N; Germani S; Giglietto N; Giommi P; Giordano F; Giroletti M; Glanzman T; Godfrey G; Grenier IA; Guiriec S; Hadasch D; Hayashida M; Hughes RE; Itoh R; Johannesson G; Johnson AS; Katagiri H; Kataoka J; Knodlseder J; Kuss M; Lande J; Larsson S; Lee SH; Longo F; Loparco F; Lott B; Lovellette MN; Lubrano P; Madejski GM; Mazziotta MN; McEnery JE; Mehault J; Michelson PF; Mitthumsiri W; Mizuno T; Monte C; Monzani ME; Morselli A; Moskalenko IV; Murgia S; Naumann-Godo M; Nishino S; Norris JP; Nuss E; Ohsugi T; Okumura A; Omodei N; Orlando E; Ozaki M; Paneque D; Panetta JH; Pelassa V; Pesce-Rollins M; Pierbattista M; Piron F; Pivato G; Porter TA; Raino S; Rando R; Rastawicki D; Razzano M; Readhead A; Reimer A; Reimer O; Reyes LC; Richards JL; Sbarra C; Sgro C; Siskind EJ; Spandre G; Spinelli P; Szostek A; Takahashi H; Tanaka T; Thayer JG; Thayer JB; Thompson DJ; Tinivella M; Torres DF; Tosti G; Troja E; Usher TL; Vandenbroucke J; Vasileiou V; Vianello G; Vitale V; Waite AP; Winer BL; Wood KS; Yang Z; Zimmer S; Moderski R; Nalewajko K; Sikora M; Villata M; Raiteri CM; Aller HD; Aller MF; Arkharov AA; Benitez E; Berdyugin A; Blinov DA; Boettcher M; Calle OJAB; Buemi CS; Carosati D; Chen WP; Diltz C; Di Paola A; Dolci M; Efimova NV; Forne E; Gurwell MA; Heidt J; Hiriart D; Jordan B; Kimeridze G; Konstantinova TS; Kopatskaya EN; Koptelova E; Kurtanidze OM; Lahteenmaki A; Larionova EG; Larionova LV; Larionov VM; Leto P; Lindfors E; Lin HC; Morozova DA; Nikolashvili MG; Nilsson K; Oksman M; Roustazadeh P; Sievers A; Sigua LA; Sillanpaa A; Takahashi T; Takalo LO; Tornikoski M; Trigilio C; Troitsky IS; Umana G; Angelakis E; Krichbaum TP; Nestoras I; Riquelme D; Krips M; Trippe S; Arai A; Kawabata KS; Sakimoto K; Sasada M; Sato S; Uemura M; Yamanaka M; Yoshida M; Belloni T; Tagliaferri G; Bonning EW; Isler J; Urry CM; Hoversten E; Falcone A; Pagani C; Stroh M. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 0004-637X. - STAMPA. - 751:2(2012), pp. 159.159-159.170. [10.1088/0004-637X/751/2/159]
MULTI-WAVELENGTH OBSERVATIONS OF BLAZAR AO 0235+164 IN THE 2008-2009 FLARING STATE
D'AMMANDO, FILIPPO;
2012
Abstract
The blazarAO 0235+164 (z=0.94) has been one of the most active objects observed by Fermi Large Area Telescope (LAT) since its launch in Summer 2008. In addition to the continuous coverage by Fermi, contemporaneous observations were carried out from the radio to gamma-ray bands between 2008 September and 2009 February. In this paper, we summarize the rich multi-wavelength data collected during the campaign (including F-GAMMA, GASP-WEBT, Kanata, OVRO, RXTE, SMARTS, Swift, and other instruments), examine the cross-correlation between the light curves measured in the different energy bands, and interpret the resulting spectral energy distributions in the context of well-known blazar emission models. We find that the gamma-ray activity is well correlated with a series of near-IR/optical flares, accompanied by an increase in the optical polarization degree. On the other hand, the X-ray light curve shows a distinct 20 day high state of unusually soft spectrum, which does not match the extrapolation of the optical/UV synchrotron spectrum. We tentatively interpret this feature as the bulk Compton emission by cold electrons contained in the jet, which requires an accretion disk corona with an effective covering factor of 19% at a distance of 100 R-g. We model the broadband spectra with a leptonic model with external radiation dominated by the infrared emission from the dusty torus.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
