<i>INTEGRAL</i> observations of the blazar 3C 454.3 in 
outburst

Pian, E.; Foschini, L.; Beckmann, V.; Soldi, S.; Türler, M.; Gehrels, N.; Ghisellini, G.; Giommi, P.; Maraschi, L.; Pursimo, T.; Raiteri, C. M.; Tagliaferri, G.; Tornikoski, M.; Tosti, G.; Treves, A.; Villata, M.; Barr, P.; Courvoisier, T. J. L.; Cocco, G. Di; Hudec, R.; Fuhrmann, L.; Malaguti, G.; Peršić, M.; Tavecchio, F.; Walter, R.

doi:10.1051/0004-6361:200600017

Cited by 90 publications

(105 citation statements)

References 38 publications

Supporting

Mentioning

103

Contrasting

Order By: Relevance

“…In 2005 it underwent a very active phase in optical and X-ray bands, triggering intensive observations in the radio, optical and X-ray (Swift, Chandra, INTEGRAL) bands (Villata et al 2006;Giommi et al 2006;Pian et al 2006). Unfortunately no γ-ray satellite was operating in the GeV domain at that time and no information was obtained in that band.…”

Section: Article Published By Edp Sciencesmentioning

confidence: 99%

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

Anderhub¹,

Antonelli²,

Antoranz³

et al. 2009

A&A

Self Cite

View full text Add to dashboard Cite

Aims. We report upper limits to the very high energy flux (E > 100 GeV) of the flat spectrum radio quasar 3C 454.3 (z = 0.859) derived by the Cherenkov telescope MAGIC during the high states of July/August and November/December 2007. We compare the upper limits derived in both time slots with the available quasi-simultaneous MeV-GeV data from the AGILE γ-ray satellite and interpret the observational results in the context of leptonic emission models. Methods. The source was observed with the MAGIC telescope during the active phases of July-August 2007 and November-December 2007 and the data were analyzed with the MAGIC standard analysis tools. For the periods around the ends of July and November, characterized by the most complete multifrequency coverage, we constructed the spectral energy distributions using our data together with nearly simultaneous multifrequency (optical, UV, X-ray and GeV) data. Results. Only upper limits can be derived from the MAGIC data. The upper limits, once corrected for the expected absorption by the extragalactic background light, together with nearly simultaneous multifrequency data, allow us to constrain the spectral energy distribution of 3C 454.3. The data are consistent with the model expectations based on inverse Compton scattering of the ambient photons from the broad line region by relativistic electrons, which robustly predicts a sharp cut-off above 20-30 GeV.

show abstract

Section: Article Published By Edp Sciencesmentioning

confidence: 99%

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

Anderhub¹,

Antonelli²,

Antoranz³

et al. 2009

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…See McHardy (2010) for a review of X-ray variability and its scaling from stellar to super-massive black holes. On the other hand, the large majority of the hard X-ray variability studies performed in the last years focused on the spectral variability of AGN at different flux levels for single bright sources or for small samples of selected objects, thanks to pointed observations of the BeppoSAX (e.g., Petrucci et al 2000;Nicastro et al 2000;de Rosa et al 2007), INTEGRAL (e.g., Pian et al 2006Pian et al , 2011Beckmann et al 2008;Lubiński et al 2010;Soldi et al 2011a;Petrucci et al 2013) and Suzaku (e.g., Reeves et al 2007;Itoh et al 2008;Terashima et al 2009;Fukazawa et al 2011;Reis et al 2012) satellites. These X-ray studies suggest different origins for the observed variability, such as changes in the amount of absorption or of its ionization, fluctuations in the seed photon flux, intrinsic modifications of the corona properties or geometry (or of the jet parameters, in case of radio loud AGN), or a variable contribution of different spectral components, with at least some of these scenarios driven by accretion rate variations.…”

Section: Introductionmentioning

confidence: 99%

Long-term variability of AGN at hard X-rays

Soldi¹,

Beckmann²,

Baumgartner³

et al. 2014

A&A

Self Cite

View full text Add to dashboard Cite

Aims. Variability at all observed wavelengths is a distinctive property of active galactic nuclei (AGN). Hard X-rays provide us with a view of the innermost regions of AGN, mostly unbiased by absorption along the line of sight. Characterizing the intrinsic hard X-ray variability of a large AGN sample and comparing it to the results obtained at lower X-ray energies can significantly contribute to our understanding of the mechanisms underlying the high-energy radiation. Methods. Swift/BAT provides us with the unique opportunity to follow, on time scales of days to years and with regular sampling, the 14-195 keV emission of the largest AGN sample available up to date for this kind of investigation. As a continuation of an early work using the first 9 months of BAT data, we study the amplitude of the variations and their dependence on subclass and on energy, for a sample of 110 radio quiet and radio loud AGN selected from the BAT 58-month survey. Results. About 80% of the AGN in the sample are found to exhibit significant variability on month-to-year time scales. In particular, radio loud sources are the most variable, and Seyfert 1.5−2 galaxies are slightly more variable than Seyfert 1, while absorbed and unabsorbed objects show similar timing properties. The amplitude of the variations and their energy dependence are incompatible with variability being driven at hard X-rays by changes in the absorption column density. In general, the variations in the 14-24 and 35-100 keV bands are correlated well, suggesting a common origin to the variability across the BAT energy band. However, radio quiet AGN display on average 10% larger variations at 14-24 keV than at 35-100 keV, and a softer-when-brighter behavior for most of the Seyfert galaxies with detectable spectral variability on a time scale of a month. In addition, sources with harder spectra are found to be more variable than softer ones, unlike what it is observed below 10 keV. These properties are generally consistent with a variable, in flux and shape, power law continuum, pivoting at energies > ∼ 50 keV, to which a constant reflection component is superposed. When the same time scales are considered, the timing properties of AGN at hard X-rays are comparable to those at lower energies, with at least some of the differences possibly ascribable to components contributing differently in the two energy domains (e.g., reflection, absorption).

show abstract

“…Dermer et al 2009, and references therein). The quasar-type blazar 3C 454.3 has received particular attention by the international astronomical community since it underwent a major outburst in 2005 (Villata et al 2006;Giommi et al 2006;Pian et al 2006;Fuhrmann et al 2006). Indeed, A&A 534, A87 (2011) after many decades of intense radio, but only mild optical activity, the source began brightening in the optical band in 2001, until in May 2005 it reached the maximum optical level ever observed, R = 12.0.…”

Section: Introductionmentioning

confidence: 99%

The long-lasting activity of 3C 454.3

Raiteri

Villata

Aller

et al. 2011

A&A

Self Cite

View full text Add to dashboard Cite

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.

show abstract

INTEGRAL observations of the blazar 3C 454.3 in outburst

Cited by 90 publications

References 38 publications

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

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

Long-term variability of AGN at hard X-rays

The long-lasting activity of 3C 454.3

Contact Info

Product

Resources

About