Multi-wavelength observations of blazar AO 0235+164 in the 2008-2009 flaring state

M. Ackermann; M. Ajello; J. Ballet; G. Barbiellini; D. Bastieri; R. Bellazzini; R. D. Blandford; E. D. Bloom; E. Bonamente; A. W. Borgland; E. Bottacini; J. Bregeon; M. Brigida; P. Bruel; R. Buehler; S. Buson; G. A. Caliandro; R. A. Cameron; P. A. Caraveo; J. M. Casandjian; E. Cavazzuti; C. Cecchi; E. Charles; A. Chekhtman; J. Chiang; S. Ciprini; R. Claus; J. Cohen-Tanugi; S. Cutini; F. D'Ammando; F. De Palma; C. D. Dermer; E. Do Couto; P. S. Drell; A. Drlica-Wagner; R. Dubois; C. Favuzzi; S. J. Fegan; E. C. Ferrara; W. B. Focke; P. Fortin; L. Fuhrmann; Y. Fukazawa; P. Fusco; F. Gargano; D. Gasparrini; N. Gehrels; S. Germani; N. Giglietto; P. Giommi; F. Giordano; M. Giroletti; T. Glanzman; G. Godfrey; I. A. Grenier; S. Guiriec; D. Hadasch; M. Hayashida; R. E. Hughes; R. Itoh; G. Jóhannesson; A. S. Johnson; H. Katagiri; J. Kataoka; J. Knödlseder; M. Kuss; J. Lande; S. Larsson; S. H. Lee; F. Longo; F. Loparco; B. Lott; M. N. Lovellette; P. Lubrano; G. M. Madejski; M. N. Mazziotta; J. E. McEnery; J. Mehault; P. F. Michelson; W. Mitthumsiri; T. Mizuno; C. Monte; M. E. Monzani; A. Morselli; I. V. Moskalenko; S. Murgia; M. Naumann-Godo; S. Nishino; J. P. Norris; E. Nuss; T. Ohsugi; A. Okumura; N. Omodei; E. Orlando; M. Ozaki; D. Paneque; J. H. Panetta; V. Pelassa; M. Pesce-Rollins; M. Pierbattista; F. Piron; G. Pivato; T. A. Porter; S. Rainò; R. Rando; D. Rastawicki; M. Razzano; A. Readhead; A. Reimer; O. Reimer; L. C. Reyes; J. L. Richards; C. Sbarra; C. Sgrò; E. J. Siskind; G. Spandre; P. Spinelli; A. Szostek; H. Takahashi; T. Tanaka; J. G. Thayer; J. B. Thayer; D. J. Thompson; M. Tinivella; D. F. Torres; G. Tosti; E. Troja; T. L. Usher; J. Vandenbroucke; V. Vasileiou; G. Vianello; V. Vitale; A. P. Waite; B. L. Winer; K. S. Wood; Z. Yang; S. Zimmer; R. Moderski; K. Nalewajko; M. Sikora; M. Villata; C. M. Raiteri; H. D. Aller; M. F. Aller; A. A. Arkharov; E. Benítez; A. Berdyugin; D. A. Blinov; M. Boettcher; O. J.A. Bravo Calle; C. S. Buemi; D. Carosati; W. P. Chen; C. Diltz; A. Dipaola; M. Dolci; N. V. Efimova; E. Forné; M. A. Gurwell; J. Heidt; D. Hiriart; B. Jordan; G. Kimeridze; T. S. Konstantinova; E. N. Kopatskaya; E. Koptelova; O. M. Kurtanidze; A. Lähteenmäki; E. G. Larionova; L. V. Larionova; V. M. Larionov; P. Leto; E. Lindfors; H. C. Lin; D. A. Morozova; M. G. Nikolashvili; K. Nilsson; M. Oksman; P. Roustazadeh; A. Sievers; L. A. Sigua; A. Sillanpää; T. Takahashi; L. O. Takalo; M. Tornikoski; C. Trigilio; I. S. Troitsky; G. Umana; E. Angelakis; T. P. Krichbaum; I. Nestoras; D. Riquelme; M. Krips; S. Trippe; A. Arai; K. S. Kawabata; K. Sakimoto; M. Sasada; S. Sato; M. Uemura; M. Yamanaka; M. Yoshida; T. Belloni; G. Tagliaferri; E. W. Bonning; J. Isler; C. M. Urry; E. Hoversten; A. Falcone; C. Pagani; M. Stroh

doi:10.1088/0004-637X/751/2/159

Multi-wavelength observations of blazar AO 0235+164 in the 2008-2009 flaring state

M. Ackermann, M. Ajello, J. Ballet, G. Barbiellini, D. Bastieri, R. Bellazzini, R. D. Blandford, E. D. Bloom, E. Bonamente, A. W. Borgland, E. Bottacini, J. Bregeon, M. Brigida, P. Bruel, R. Buehler, S. Buson, G. A. Caliandro, R. A. Cameron, P. A. Caraveo, J. M. CasandjianE. Cavazzuti, C. Cecchi, E. Charles, A. Chekhtman, J. Chiang, S. Ciprini, R. Claus, J. Cohen-Tanugi, S. Cutini, F. D'Ammando, F. De Palma, C. D. Dermer, E. Do Couto, P. S. Drell, A. Drlica-Wagner, R. Dubois, C. Favuzzi, S. J. Fegan, E. C. Ferrara, W. B. Focke, P. Fortin, L. Fuhrmann, Y. Fukazawa, P. Fusco, F. Gargano, D. Gasparrini, N. Gehrels, S. Germani, N. Giglietto, P. Giommi, F. Giordano, M. Giroletti, T. Glanzman, G. Godfrey, I. A. Grenier, S. Guiriec, D. Hadasch, M. Hayashida, R. E. Hughes, R. Itoh, G. Jóhannesson, A. S. Johnson, H. Katagiri, J. Kataoka, J. Knödlseder, M. Kuss, J. Lande, S. Larsson, S. H. Lee, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, G. M. Madejski, M. N. Mazziotta, J. E. McEnery, J. Mehault, P. F. Michelson, W. Mitthumsiri, T. Mizuno, C. Monte, M. E. Monzani, A. Morselli, I. V. Moskalenko, S. Murgia, M. Naumann-Godo, S. Nishino, J. P. Norris, E. Nuss, T. Ohsugi, A. Okumura, N. Omodei, E. Orlando, M. Ozaki, D. Paneque, J. H. Panetta, V. Pelassa, M. Pesce-Rollins, M. Pierbattista, F. Piron, G. Pivato, T. A. Porter, S. Rainò, R. Rando, D. Rastawicki, M. Razzano, A. Readhead, A. Reimer, O. Reimer, L. C. Reyes, J. L. Richards, C. Sbarra, C. Sgrò, E. J. Siskind, G. Spandre, P. Spinelli, A. Szostek, H. Takahashi, T. Tanaka, J. G. Thayer, J. B. Thayer, D. J. Thompson, M. Tinivella, D. F. Torres, G. Tosti, E. Troja, T. L. Usher, J. Vandenbroucke, V. Vasileiou, G. Vianello, V. Vitale, A. P. Waite, B. L. Winer, K. S. Wood, Z. Yang, S. Zimmer, R. Moderski, K. Nalewajko, M. Sikora, M. Villata, C. M. Raiteri, H. D. Aller, M. F. Aller, A. A. Arkharov, E. Benítez, A. Berdyugin, D. A. Blinov, M. Boettcher, O. J.A. Bravo Calle, C. S. Buemi, D. Carosati, W. P. Chen, C. Diltz, A. Dipaola, M. Dolci, N. V. Efimova, E. Forné, M. A. Gurwell, J. Heidt, D. Hiriart, B. Jordan, G. Kimeridze, T. S. Konstantinova, E. N. Kopatskaya, E. Koptelova, O. M. Kurtanidze, A. Lähteenmäki, E. G. Larionova, L. V. Larionova, V. M. Larionov, P. Leto, E. Lindfors, H. C. Lin, D. A. Morozova, M. G. Nikolashvili, K. Nilsson, M. Oksman, P. Roustazadeh, A. Sievers, L. A. Sigua, A. Sillanpää, T. Takahashi, L. O. Takalo, M. Tornikoski, C. Trigilio, I. S. Troitsky, G. Umana, E. Angelakis, T. P. Krichbaum, I. Nestoras, D. Riquelme, M. Krips, S. Trippe, A. Arai, K. S. Kawabata, K. Sakimoto, M. Sasada, S. Sato, M. Uemura, M. Yamanaka, M. Yoshida, T. Belloni, G. Tagliaferri, E. W. Bonning, J. Isler, C. M. Urry, E. Hoversten, A. Falcone, C. Pagani, M. Stroh

Research output: Contribution to journal › Article › peer-review

58 Scopus citations

Abstract

The blazar AO 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 γ-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 γ-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.

Original language	English (US)
Article number	159
Journal	Astrophysical Journal
Volume	751
Issue number	2
DOIs	https://doi.org/10.1088/0004-637X/751/2/159
State	Published - Jun 1 2012

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

Access to Document

10.1088/0004-637X/751/2/159

Cite this

Ackermann, M., Ajello, M., Ballet, J., Barbiellini, G., Bastieri, D., Bellazzini, R., Blandford, R. D., Bloom, E. D., Bonamente, E., Borgland, A. W., Bottacini, E., Bregeon, J., Brigida, M., Bruel, P., Buehler, R., Buson, S., Caliandro, G. A., Cameron, R. A., Caraveo, P. A., ... Stroh, M. (2012). Multi-wavelength observations of blazar AO 0235+164 in the 2008-2009 flaring state. Astrophysical Journal, 751(2), Article 159. https://doi.org/10.1088/0004-637X/751/2/159

@article{523700fd485645afb26358bb8f0338df,

title = "Multi-wavelength observations of blazar AO 0235+164 in the 2008-2009 flaring state",

abstract = "The blazar AO 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 γ-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 γ-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.",

author = "M. Ackermann and M. Ajello and J. Ballet and G. Barbiellini and D. Bastieri and R. Bellazzini and Blandford, {R. D.} and Bloom, {E. D.} and E. Bonamente and Borgland, {A. W.} and E. Bottacini and J. Bregeon and M. Brigida and P. Bruel and R. Buehler and S. Buson and Caliandro, {G. A.} and Cameron, {R. A.} and Caraveo, {P. A.} and Casandjian, {J. M.} and E. Cavazzuti and C. Cecchi and E. Charles and A. Chekhtman and J. Chiang and S. Ciprini and R. Claus and J. Cohen-Tanugi and S. Cutini and F. D'Ammando and {De Palma}, F. and Dermer, {C. D.} and {Do Couto}, E. and Drell, {P. S.} and A. Drlica-Wagner and R. Dubois and C. Favuzzi and Fegan, {S. J.} and Ferrara, {E. C.} and Focke, {W. B.} and P. Fortin and L. Fuhrmann and Y. Fukazawa and P. Fusco and F. Gargano and D. Gasparrini and N. Gehrels and S. Germani and N. Giglietto and P. Giommi and F. Giordano and M. Giroletti and T. Glanzman and G. Godfrey and Grenier, {I. A.} and S. Guiriec and D. Hadasch and M. Hayashida and Hughes, {R. E.} and R. Itoh and G. J{\'o}hannesson and Johnson, {A. S.} and H. Katagiri and J. Kataoka and J. Kn{\"o}dlseder and M. Kuss and J. Lande and S. Larsson and Lee, {S. H.} and F. Longo and F. Loparco and B. Lott and Lovellette, {M. N.} and P. Lubrano and Madejski, {G. M.} and Mazziotta, {M. N.} and McEnery, {J. E.} and J. Mehault and Michelson, {P. F.} and W. Mitthumsiri and T. Mizuno and C. Monte and Monzani, {M. E.} and A. Morselli and Moskalenko, {I. V.} and S. Murgia and M. Naumann-Godo and S. Nishino and Norris, {J. P.} and E. Nuss and T. Ohsugi and A. Okumura and N. Omodei and E. Orlando and M. Ozaki and D. Paneque and Panetta, {J. H.} and V. Pelassa and M. Pesce-Rollins and M. Pierbattista and F. Piron and G. Pivato and Porter, {T. A.} and S. Rain{\`o} and R. Rando and D. Rastawicki and M. Razzano and A. Readhead and A. Reimer and O. Reimer and Reyes, {L. C.} and Richards, {J. L.} and C. Sbarra and C. Sgr{\`o} and Siskind, {E. J.} and G. Spandre and P. Spinelli and A. Szostek and H. Takahashi and T. Tanaka and Thayer, {J. G.} and Thayer, {J. B.} and Thompson, {D. J.} and M. Tinivella and Torres, {D. F.} and G. Tosti and E. Troja and Usher, {T. L.} and J. Vandenbroucke and V. Vasileiou and G. Vianello and V. Vitale and Waite, {A. P.} and Winer, {B. L.} and Wood, {K. S.} and Z. Yang and S. Zimmer and R. Moderski and K. Nalewajko and M. Sikora and M. Villata and Raiteri, {C. M.} and Aller, {H. D.} and Aller, {M. F.} and Arkharov, {A. A.} and E. Ben{\'i}tez and A. Berdyugin and Blinov, {D. A.} and M. Boettcher and {Bravo Calle}, {O. J.A.} and Buemi, {C. S.} and D. Carosati and Chen, {W. P.} and C. Diltz and A. Dipaola and M. Dolci and Efimova, {N. V.} and E. Forn{\'e} and Gurwell, {M. A.} and J. Heidt and D. Hiriart and B. Jordan and G. Kimeridze and Konstantinova, {T. S.} and Kopatskaya, {E. N.} and E. Koptelova and Kurtanidze, {O. M.} and A. L{\"a}hteenm{\"a}ki and Larionova, {E. G.} and Larionova, {L. V.} and Larionov, {V. M.} and P. Leto and E. Lindfors and Lin, {H. C.} and Morozova, {D. A.} and Nikolashvili, {M. G.} and K. Nilsson and M. Oksman and P. Roustazadeh and A. Sievers and Sigua, {L. A.} and A. Sillanp{\"a}{\"a} and T. Takahashi and Takalo, {L. O.} and M. Tornikoski and C. Trigilio and Troitsky, {I. S.} and G. Umana and E. Angelakis and Krichbaum, {T. P.} and I. Nestoras and D. Riquelme and M. Krips and S. Trippe and A. Arai and Kawabata, {K. S.} and K. Sakimoto and M. Sasada and S. Sato and M. Uemura and M. Yamanaka and M. Yoshida and T. Belloni and G. Tagliaferri and Bonning, {E. W.} and J. Isler and Urry, {C. M.} and E. Hoversten and A. Falcone and C. Pagani and M. Stroh",

year = "2012",

month = jun,

day = "1",

doi = "10.1088/0004-637X/751/2/159",

language = "English (US)",

volume = "751",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "2",

}

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, D'Ammando, F, De Palma, F, Dermer, CD, Do Couto, E, 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, Jóhannesson, G, Johnson, AS, Katagiri, H, Kataoka, J, Knödlseder, 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, Rainò, S, Rando, R, Rastawicki, D, Razzano, M, Readhead, A, Reimer, A, Reimer, O, Reyes, LC, Richards, JL, Sbarra, C, Sgrò, 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, Benítez, E, Berdyugin, A, Blinov, DA, Boettcher, M, Bravo Calle, OJA, Buemi, CS, Carosati, D, Chen, WP, Diltz, C, Dipaola, A, Dolci, M, Efimova, NV, Forné, E, Gurwell, MA, Heidt, J, Hiriart, D, Jordan, B, Kimeridze, G, Konstantinova, TS, Kopatskaya, EN, Koptelova, E, Kurtanidze, OM, Lähteenmäki, 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, Sillanpää, 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 2012, 'Multi-wavelength observations of blazar AO 0235+164 in the 2008-2009 flaring state', Astrophysical Journal, vol. 751, no. 2, 159. https://doi.org/10.1088/0004-637X/751/2/159

TY - JOUR

T1 - Multi-wavelength observations of blazar AO 0235+164 in the 2008-2009 flaring state

AU - Ackermann, M.

AU - Ajello, M.

AU - Ballet, J.

AU - Barbiellini, G.

AU - Bastieri, D.

AU - Bellazzini, R.

AU - Blandford, R. D.

AU - Bloom, E. D.

AU - Bonamente, E.

AU - Borgland, A. W.

AU - Bottacini, E.

AU - Bregeon, J.

AU - Brigida, M.

AU - Bruel, P.

AU - Buehler, R.

AU - Buson, S.

AU - Caliandro, G. A.

AU - Cameron, R. A.

AU - Caraveo, P. A.

AU - Casandjian, J. M.

AU - Cavazzuti, E.

AU - Cecchi, C.

AU - Charles, E.

AU - Chekhtman, A.

AU - Chiang, J.

AU - Ciprini, S.

AU - Claus, R.

AU - Cohen-Tanugi, J.

AU - Cutini, S.

AU - D'Ammando, F.

AU - De Palma, F.

AU - Dermer, C. D.

AU - Do Couto, E.

AU - Drell, P. S.

AU - Drlica-Wagner, A.

AU - Dubois, R.

AU - Favuzzi, C.

AU - Fegan, S. J.

AU - Ferrara, E. C.

AU - Focke, W. B.

AU - Fortin, P.

AU - Fuhrmann, L.

AU - Fukazawa, Y.

AU - Fusco, P.

AU - Gargano, F.

AU - Gasparrini, D.

AU - Gehrels, N.

AU - Germani, S.

AU - Giglietto, N.

AU - Giommi, P.

AU - Giordano, F.

AU - Giroletti, M.

AU - Glanzman, T.

AU - Godfrey, G.

AU - Grenier, I. A.

AU - Guiriec, S.

AU - Hadasch, D.

AU - Hayashida, M.

AU - Hughes, R. E.

AU - Itoh, R.

AU - Jóhannesson, G.

AU - Johnson, A. S.

AU - Katagiri, H.

AU - Kataoka, J.

AU - Knödlseder, J.

AU - Kuss, M.

AU - Lande, J.

AU - Larsson, S.

AU - Lee, S. H.

AU - Longo, F.

AU - Loparco, F.

AU - Lott, B.

AU - Lovellette, M. N.

AU - Lubrano, P.

AU - Madejski, G. M.

AU - Mazziotta, M. N.

AU - McEnery, J. E.

AU - Mehault, J.

AU - Michelson, P. F.

AU - Mitthumsiri, W.

AU - Mizuno, T.

AU - Monte, C.

AU - Monzani, M. E.

AU - Morselli, A.

AU - Moskalenko, I. V.

AU - Murgia, S.

AU - Naumann-Godo, M.

AU - Nishino, S.

AU - Norris, J. P.

AU - Nuss, E.

AU - Ohsugi, T.

AU - Okumura, A.

AU - Omodei, N.

AU - Orlando, E.

AU - Ozaki, M.

AU - Paneque, D.

AU - Panetta, J. H.

AU - Pelassa, V.

AU - Pesce-Rollins, M.

AU - Pierbattista, M.

AU - Piron, F.

AU - Pivato, G.

AU - Porter, T. A.

AU - Rainò, S.

AU - Rando, R.

AU - Rastawicki, D.

AU - Razzano, M.

AU - Readhead, A.

AU - Reimer, A.

AU - Reimer, O.

AU - Reyes, L. C.

AU - Richards, J. L.

AU - Sbarra, C.

AU - Sgrò, C.

AU - Siskind, E. J.

AU - Spandre, G.

AU - Spinelli, P.

AU - Szostek, A.

AU - Takahashi, H.

AU - Tanaka, T.

AU - Thayer, J. G.

AU - Thayer, J. B.

AU - Thompson, D. J.

AU - Tinivella, M.

AU - Torres, D. F.

AU - Tosti, G.

AU - Troja, E.

AU - Usher, T. L.

AU - Vandenbroucke, J.

AU - Vasileiou, V.

AU - Vianello, G.

AU - Vitale, V.

AU - Waite, A. P.

AU - Winer, B. L.

AU - Wood, K. S.

AU - Yang, Z.

AU - Zimmer, S.

AU - Moderski, R.

AU - Nalewajko, K.

AU - Sikora, M.

AU - Villata, M.

AU - Raiteri, C. M.

AU - Aller, H. D.

AU - Aller, M. F.

AU - Arkharov, A. A.

AU - Benítez, E.

AU - Berdyugin, A.

AU - Blinov, D. A.

AU - Boettcher, M.

AU - Bravo Calle, O. J.A.

AU - Buemi, C. S.

AU - Carosati, D.

AU - Chen, W. P.

AU - Diltz, C.

AU - Dipaola, A.

AU - Dolci, M.

AU - Efimova, N. V.

AU - Forné, E.

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AU - Hiriart, D.

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AU - Kimeridze, G.

AU - Konstantinova, T. S.

AU - Kopatskaya, E. N.

AU - Koptelova, E.

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AU - Lähteenmäki, A.

AU - Larionova, E. G.

AU - Larionova, L. V.

AU - Larionov, V. M.

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AU - Lindfors, E.

AU - Lin, H. C.

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AU - Nikolashvili, M. G.

AU - Nilsson, K.

AU - Oksman, M.

AU - Roustazadeh, P.

AU - Sievers, A.

AU - Sigua, L. A.

AU - Sillanpää, A.

AU - Takahashi, T.

AU - Takalo, L. O.

AU - Tornikoski, M.

AU - Trigilio, C.

AU - Troitsky, I. S.

AU - Umana, G.

AU - Angelakis, E.

AU - Krichbaum, T. P.

AU - Nestoras, I.

AU - Riquelme, D.

AU - Krips, M.

AU - Trippe, S.

AU - Arai, A.

AU - Kawabata, K. S.

AU - Sakimoto, K.

AU - Sasada, M.

AU - Sato, S.

AU - Uemura, M.

AU - Yamanaka, M.

AU - Yoshida, M.

AU - Belloni, T.

AU - Tagliaferri, G.

AU - Bonning, E. W.

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AU - Hoversten, E.

AU - Falcone, A.

AU - Pagani, C.

AU - Stroh, M.

PY - 2012/6/1

Y1 - 2012/6/1

N2 - The blazar AO 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 γ-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 γ-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.

AB - The blazar AO 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 γ-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 γ-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.

UR - http://www.scopus.com/inward/record.url?scp=84861396505&partnerID=8YFLogxK

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U2 - 10.1088/0004-637X/751/2/159

DO - 10.1088/0004-637X/751/2/159

M3 - Article

AN - SCOPUS:84861396505

SN - 0004-637X

VL - 751

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

M1 - 159

ER -

Multi-wavelength observations of blazar AO 0235+164 in the 2008-2009 flaring state

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