MAGIC upper limits to the VHE gamma-ray flux  of 3C 454.3 in
 high emission state

Anderhub, H.; Antonelli, L. A.; Antoranz, P.; Backes, Michael; Baixeras, C.; Balestra, S.; Barrio, J. A.; Bartko, H.; Bastieri, D.; González, J. Becerra; Becker, J.; Bednarek, W.; Berger, K.; Bernardini, E.; Biland, A.; Böck, R.; Bonnoli, G.; Bordas, P.; Tridon, D. Borla; Bosch‐Ramon, V.; Bretz, T.; Britvitch, I.; Cámara, Miguel; Carmona, E.; Commichau, S.; Contreras, J. L.; Cortina, J.; Costado, M. T.; Covino, S.; Curtef, V.; Dazzi, F.; Angelis, A. De; Pozo, E. De Cea del; Reyes, R. de los; Lotto, B. De; María, Mónica; Sabata, F. De; Mendez, C. Delgado; Domínguez, A.; Dorner, D.; Doro, M.; Elsäesser, D.; Errando, M.; Ferenc, D.; Fernández, E.; Firpo, R.; Fonseca, M. V.; Font, L.; Galante, N.; López, R. J. García; Garczarczyk, M.; Gaug, M.; Göebel, F.; Hadasch, D.; Hayashida, M.; Herrero, A.; Höhne-Mönch, D.; Hose, J.; Hsu, C. C.; Huber, Stefan; Jogler, T.; Kranich, D.; Barbera, A. La; Laille, A.; Leonardo, E.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; Lorenz, E.; Majumdar, P.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martı́nez, M.; Mazin, D.; Meucci, M.; Meyer, M.; Miranda, J. M.; Mirzoyan, R.; Moldón, J.; Moles, M.; Moralejo, A.; Nieto, D.; Nilsson, K.; Ninković, J.; Otte, N.; Oya, I.; Paoletti, R.; Paredes, J. M.; Pasanen, M.; Pascoli, D.; Pauß, F.; Pegna, R.; Pérez-Torres, M. A.; Peršić, M.; Peruzzo, L.; Prada, Francisco; Prandini, E.; Puchades, N.; Rhode, W.; Ribó, M.; Rico, J.; Rissi, M.; Robert, A.; Rügamer, S.; Saggion, A.; Saito, T.; Salvati, M.; Sánchez‐Conde, Miguel A.; Sartori, P.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schweizer, T.; Shayduk, M.; Shinozaki, K.; Shore, Steven N.; Sidro, N.; Sierpowska-Bartosik, A.; Sillanpää, A.; Sobczyńska, D.; Spanier, F.; Stamerra, A.; Stark, L. S.; Takalo, L. O.; Tavecchio, F.; Temnikov, P.; Tescaro, D.; Teshima, M.; Tluczykont, M.; Torres, D. F.; Turini, N.; Vankov, H.; Venturini, A.; Vitale, V.; Wagner, R. M.; Wittek, W.; Zabalza, V.; Zandanel, F.; Zanin, R.; Zapatero, J.; Vercellone, S.; Donnarumma, I.; D’Ammando, F.; Tavani, M.

doi:10.1051/0004-6361/200811326

Cited by 18 publications

(16 citation statements)

References 48 publications

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“…On the other hand, the soft X-ray data were only a little bit lower than in November. Despite the softer synchrotron bump, γ -ray data showed in the SED the persistence of a hard peak at 1 GeV, similar to the higher states observed by AGILE in 2007 July and 2007 November (Anderhub et al 2009;Vercellone et al 2009). In fact, the December γ -ray spectrum (characterized by a photon index of ∼1.78) is consistent with those obtained during the two previous AGILE observations.…”

Section: Spectral Modelingsupporting

confidence: 68%

“…The source was found to be in flaring state with an average γ -ray flux above 100 MeV of ∼250 × 10 −8 photons cm −2 s −1 , which is typical of its high γ -ray state (Vercellone et al 2008(Vercellone et al , 2009Anderhub et al 2009). As in the case of the previous multifrequency campaign (2007 November; Vercellone et al 2009), the source was continuously monitored in γ -rays as well as in the optical energy bands.…”

Section: Timing Analysismentioning

confidence: 99%

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MULTIWAVELENGTH OBSERVATIONS OF 3C 454.3. II. THEAGILE2007 DECEMBER CAMPAIGN

Donnarumma

Pucella

Vittorini

et al. 2009

ApJ

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We report on the second Astrorivelatore Gamma a Immagini Leggero (AGILE) multiwavelength campaign of the blazar 3C 454.3 during the first half of 2007 December. This campaign involved AGILE, Spitzer, Swift, Suzaku, the Whole Earth Blazar Telescope (WEBT) consortium, the Rapid Eye Mount (REM), and the Multicolor Imaging Telescopes for Survey and Monstrous Explosions (MITSuME) telescopes, offering a broadband coverage that allowed for a simultaneous sampling of the synchrotron and inverse Compton (IC) emissions. The two-week AGILE monitoring was accompanied by radio to optical monitoring by WEBT and REM, and by sparse observations in midinfrared and soft/hard X-ray energy bands performed by means of Target of Opportunity observations by Spitzer, Swift, and Suzaku, respectively. The source was detected with an average flux of ∼250 × 10 −8 photons cmabove 100 MeV, typical of its flaring states. The simultaneous optical and γ -ray monitoring allowed us to study the time lag associated with the variability in the two energy bands, resulting in a possible one-day delay of the γ -ray emission with respect to the optical one. From the simultaneous optical and γ -ray fast flare detected on December 12, we can constrain the delay between the γ -ray and optical emissions within 12 hr. Moreover, we obtain three spectral energy distributions (SEDs) with simultaneous data for 2007 December 5, 13, and 15, characterized by the widest multifrequency coverage. We found that a model with an external Compton on seed photons by a standard disk and reprocessed by the broad-line regions does not describe in a satisfactory way the SEDs of 2007 December 5, 13, and 15. An additional contribution, possibly from the hot corona with T = 10 6 K surrounding the jet, is required to account simultaneously for the softness of the synchrotron and the hardness of the IC emissions during those epochs.

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Section: Spectral Modelingsupporting

confidence: 68%

Section: Timing Analysismentioning

confidence: 99%

MULTIWAVELENGTH OBSERVATIONS OF 3C 454.3. II. THEAGILE2007 DECEMBER CAMPAIGN

Donnarumma

Pucella

Vittorini

et al. 2009

ApJ

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“…AGILE performed a target of opportunity (ToO) re-pointing towards the source and detected it in a very high γ-ray state (Vercellone et al 2008, hereafter V08). In November and December 2007, AGILE detected high γ-ray activity from 3C 454.3, triggering multiwavelength ToO campaigns, whose results are reported in Vercellone et al (2009, hereafter Paper I), in Donnarumma et al (2009, hereafter Paper II), and in Anderhub et al (2009), respectively. Paper I and Paper II demonstrated that to fit the simultaneous broadband SEDs from radio to γ-ray data, inverse Compton (IC) scattering of external photons from the broad line region (BLR) off the relativistic electrons in the jet was required.…”

mentioning

confidence: 60%

Multiwavelength Observations of 3c 454.3. Iii. Eighteen Months of Agile Monitoring of the “Crazy Diamond”

Vercellone

D’Ammando

Vittorini

et al. 2010

ApJ

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We also carried out simultaneous Swift observations during all AGILE campaigns. Swift/XRT detected 3C 454.3 with an observed flux in the 2-10 keV energy band in the range (0.9 − 7.5) × 10 −11 erg cm −2 s −1 and a photon index in the range Γ XRT = 1.33 − 2.04. In the 15-150 keV energy band, when detected, the source has an average flux of about 5 mCrab.GASP-WEBT monitored 3C 454.3 during the whole 2007-2008 period in the radio, millimeter, near-IR, and optical bands. The observations show an extremely variable behavior at all frequencies, with flux peaks almost simultaneous with those at higher energies. A correlation analysis between the optical and the γ-ray fluxes shows that the γ-optical correlation occurs with a time lag of τ = −0.4 +0.6 −0.8 days, consistent with previous findings for this source.An analysis of 15 GHz and 43 GHz VLBI core radio flux observations in the period 2007 July -2009 February shows an increasing trend of the core radio flux, anti-correlated with the higher frequency data, allowing us to derive the value of the source magnetic field.Finally, the modeling of the broad-band spectral energy distributions (SEDs) for the still unpublished data, and the behavior of the long-term light curves in different energy bands, allow us to compare the jet properties during different emission states, and to study the geometrical properties of the jet on a time-span longer than one year.

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“…Rotations of the optical polarisation vector both clockwise and counterclockwise were detected by Sasada et al (2010). In contrast, observations at very high energies (E > 100 GeV) by the Cherenkov telescope MAGIC resulted in only upper limits (Anderhub et al 2009).…”

Section: Introductionmentioning

confidence: 92%

The long-lasting activity of 3C 454.3

Raiteri

Villata

Aller

et al. 2011

A&A

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Context. The blazar 3C 454.3 is one of the most active sources from the radio to the γ-ray frequencies observed in the past few years. Aims. We present multiwavelength observations of this source from April 2008 to March 2010. The radio to optical data are mostly from the GASP-WEBT, UV and X-ray data from Swift, and γ-ray data from the AGILE and Fermi satellites. The aim is to understand the connection among emissions at different frequencies and to derive information on the emitting jet. Methods. Light curves in 18 bands were carefully assembled to study flux variability correlations. We improved the calibration of optical-UV data from the UVOT and OM instruments and estimated the Lyα flux to disentangle the contributions from different components in this spectral region. Results. The observations reveal prominent variability above 8 GHz. In the optical-UV band, the variability amplitude decreases with increasing frequency due to a steadier radiation from both a broad line region and an accretion disc. The optical flux reaches nearly the same levels in the 2008-2009 and 2009-2010 observing seasons; the mm one shows similar behaviour, whereas the γ and X-ray flux levels rise in the second period. Two prominent γ-ray flares in mid 2008 and late 2009 show a double-peaked structure, with a variable γ/optical flux ratio. The X-ray flux variations seem to follow the γ-ray and optical ones by about 0.5 and 1 d, respectively. Conclusions. We interpret the multifrequency behaviour in terms of an inhomogeneous curved jet, where synchrotron radiation of increasing wavelength is produced in progressively outer and wider jet regions, which can change their orientation in time. In particular, we assume that the long-term variability is due to this geometrical effect. By combining the optical and mm light curves to fit the γ and X-ray ones, we find that the γ (X-ray) emission may be explained by inverse-Comptonisation of synchrotron optical (IR) photons by their parent relativistic electrons (SSC process). A slight, variable misalignment between the synchrotron and Comptonisation zones would explain the increased γ and X-ray flux levels in 2009-2010, as well as the change in the γ/optical flux ratio during the outbursts peaks. The time delays of the X-ray flux changes after the γ, and optical ones are consistent with the proposed scenario.

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MAGIC upper limits to the VHE gamma-ray flux of 3C 454.3 in high emission state

Cited by 18 publications

References 48 publications

MULTIWAVELENGTH OBSERVATIONS OF 3C 454.3. II. THEAGILE2007 DECEMBER CAMPAIGN

MULTIWAVELENGTH OBSERVATIONS OF 3C 454.3. II. THEAGILE2007 DECEMBER CAMPAIGN

Multiwavelength Observations of 3c 454.3. Iii. Eighteen Months of Agile Monitoring of the “Crazy Diamond”

The long-lasting activity of 3C 454.3

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