We present the results from the Suzaku X-ray observations of five flat-spectrum radio quasars (FSRQs), namely PKS 0208–512, Q 0827+243, PKS 1127–145, PKS 1510–089, and 3C 454.3. All these sources were additionally monitored simultaneously or quasi-simultaneously by the Fermi satellite in gamma rays and the Swift UVOT in the UV and optical bands, respectively. We constructed their broadband spectra covering the frequency range from 1014 Hz up to 1025 Hz, and those reveal the nature of high-energy emission of luminous blazars in their low-activity states. The analyzed X-ray spectra are well fitted by a power-law model with photoelectric absorption. In the case of PKS 0208–512, PKS 1127–145, and 3C 454.3, the X-ray continuum showed indication of hardening at low energies. Moreover, when compared with the previous X-ray observations, we see a significantly increasing contribution of low-energy photons to the total X-ray fluxes when the sources are getting fainter. The same behavior can be noted in the Suzaku data alone. A likely explanation involves a variable, flat-spectrum component produced via inverse-Compton emission, plus an additional, possibly steady soft X-ray component prominent when the source gets fainter. This soft X-ray excess is represented either by a steep power-law (photon indices Γ ~ 3-5) or a blackbody-type emission with temperatures kT ~ 0.1-0.2 keV. We model the broadband spectra of the five observed FSRQs using synchrotron self-Compton and/or external-Compton radiation models. Our modeling suggests that the difference between the low- and high-activity states in luminous blazars is due to the different total kinetic power of the jet, most likely related to varying bulk Lorentz factor of the outflow within the blazar emission zone.
|Autori:||Abdo AA; Ackermann M; Ajello M; Antolini E; Baldini L; Ballet J; Barbiellini G; Baring MG; Bastieri D; Bechtol K; Bellazzini R; Berenji B; Blandford RD; Bloom ED; Bonamente E; Borgland AW; Bregeon J; Brez A; Brigida M; Bruel P; Buehler R; Buson S; Caliandro GA; Cameron RA; Carrigan S; Casandjian JM; Cavazzuti E; Cecchi C; Celik O; Chekhtman A; Chen AW; Chiang J; Ciprini S; Claus R; Cohen-Tanugi J; Colafrancesco S; Conrad J; Cutini S; Dermer CD; de Palma F; Digel SW; Silva EDE; Drell PS; Dubois R; Dumora D; Farnier C; Favuzzi C; Fegan SJ; Ferrara EC; Focke WB; Frailis M; Fukazawa Y; Fusco P; Gargano F; Gasparrini D; Gehrels N; Giebels B; Giglietto N; Giommi P; Giordano F; Giroletti M; Glanzman T; Godfrey G; Grandi P; Grenier IA; Guillemot L; Guiriec S; Hadasch D; Harding AK; Hayashida M; Horan D; Hughes RE; Itoh R; Jackson MS; Johannesson G; Johnson AS; Johnson WN; Kamae T; Katagiri H; Kataoka J; Kawai N; Knodlseder J; Kuss M; Lande J; Latronico L; Longo F; Loparco F; Lott B; Lovellette MN; Lubrano P; Madejski GM; Makeev A; Mazziotta MN; McEnery JE; McGlynn S; Meurer C; Michelson PF; Mitthumsiri W; Mizuno T; Monte C; Monzani ME; Morselli A; Moskalenko IV; Murgia S; Nestoras I; Nolan PL; Norris JP; Nuss E; Ohsugi T; Okumura A; Orlando E; Ormes JF; Ozaki M; Paneque D; Panetta JH; Parent D; Pelassa V; Pepe M; Pesce-Rollins M; Piron F; Porter TA; Raino S; Rando R; Razzano M; Reimer A; Reimer O; Reyes LC; Rodriguez AY; Roth M; Ryde F; Sadrozinski HFW; Sambruna R; Sander A; Sato R; Sgro C; Shaw MS; Siskind EJ; Smith PD; Spandre G; Spinelli P; Stawarz L; Stecker FW; Strickman MS; Suson DJ; Takahashi H; Takahashi T; Tanaka T; Thayer JB; Thayer JG; Thompson DJ; Tibolla O; Torres DF; Tosti G; Tramacere A; Uchiyama Y; Usher TL; Vasileiou V; Vilchez N; Villata M; Vitale V; von Kienlin A; Waite AP; Wang P; Winer BL; Wood KS; Yang Z; Ylinen T; Ziegler M; Tavecchio F; Sikora M; Schady P; Roming P; Chester MM; Maraschi L|
|Titolo:||SUZAKU OBSERVATIONS OF LUMINOUS QUASARS: REVEALING THE NATURE OF HIGH-ENERGY BLAZAR EMISSION IN LOW-LEVEL ACTIVITY STATES|
|Anno del prodotto:||2010|
|Digital Object Identifier (DOI):||10.1088/0004-637X/716/1/835|
|Appare nelle tipologie:||1.1 Articolo in rivista|