Multi-frequency monitoring of γ-ray loud blazars

Bach, U.; Raiteri, C. M.; Villata, M.; Fuhrmann, L.; Buemi, C. S.; Larionov, V. M.; Leto, P.; Arkharov, A. A.; Coloma, J. M.; Paola, Andrea; Dolci, M.; Ефимова, Н. В.; Forné, E.; Ibrahimov, M.; Hagen-Thorn, V. A.; Константинова, Т. С.; Kopatskaya, E. N.; Lanteri, L.; Kurtanidze, O. M.; Maccaferri, G.; Nikolashvili, M. G.; Orlati, A.; Ros, Javier; Tosti, G.; Trigilio, C.; Umana, G.

doi:10.1051/0004-6361:20066561

Cited by 38 publications

(22 citation statements)

References 89 publications

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“…Fan & Lin (2000) propose a periodic light curve for PKS 0851+202, with a period of 12 years. Our results are in agreement with the magnitudes expected for this periodic variability and with the values observed by Bach et al (2007).…”

Section: Resultssupporting

confidence: 93%

“…Multi-wavelength studies have detected correlated variability, mostly with flares from radio to X-rays, including optical and near IR bands (Bach et al 2007;Osterman Meyer et al 2009;Fromm et al 2011). CTA 102 also shows a jet with superluminal motions of up to 21 c, derived from VLBI observations (see, Jorstad et al 2001;Rantakyrö et al 2003;Jorstad et al 2005).…”

Section: Pks 1510−089mentioning

confidence: 99%

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Optical flux behaviour of a sample ofFermiblazars

Marchesini

Andruchow

Cellone

et al. 2016

A&A

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Aims. We aim at investigating the time-behaviour of a sample of gamma-ray blazars. We present the results from a 13 monthlong optical photometry monitoring campaign of the blazars PKS 0048−097, PKS 0754+100, [HB89] 0827+243, PKS 0851+202, PKS 1253−055, PKS 1510−089, PKS 1749+096, PKS 2230+114 and PKS 2251+158. Methods. We analyse the variability of each object, focusing on different time-scales (long term, short term, and microvariability), in an attempt to achieve a statistical comparison of the results. Results. After applying a geometric model to explain the variability results, we found that it is possible that a slight change in the direction of the jet generates the variations detected in some objects during this campaign.

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Section: Resultssupporting

confidence: 93%

Section: Pks 1510−089mentioning

confidence: 99%

Optical flux behaviour of a sample ofFermiblazars

Marchesini

Andruchow

Cellone

et al. 2016

A&A

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“…That the synchrotron component of PKS 1510−089 peaks around 10 13 Hz (see Bach et al 2007;Nieppola et al 2008) allows us to observe these thermal features in this source. In fact, around 10 15 Hz, a rising emission is visible in the spectrum and is likely a manifestation of the big blue bump produced by the accretion disk, as already discussed for this source by Malkan & Moore (1986) and Pian & Treves (1993); moreover, a hint of the little blue bump seems to appear in the SED of the source at 10 14.5 Hz.…”

Section: Thermal Emission Componentsmentioning

confidence: 84%

AGILE detection of a rapid γ-ray flare from the blazar PKS 1510-089 during the GASP-WEBT monitoring

D’Ammando

Pucella²,

Raiteri

et al. 2009

A&A

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Aims. We report the detection by the AGILE satellite of a rapid γ-ray flare from the source 1AGL J1511−0908, associated with the powerful γ-ray quasar PKS 1510−089, during a pointing centered on the Galactic center region from 1 March to 30 March 2008. This source has been continuosly monitored in the radio-to-optical bands by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT). Moreover, the γ-ray flaring episode triggered three ToO observations by the Swi f t satellite in three consecutive days, starting from 20 March 2008. The quasisimultaneous radio-to-optical, UV, X-ray and γ-ray coverage allows us to make a detailed study of the multifrequency time evolution, the spectral energy distribution of this source, and its theoretical interpretation based on the synchrotron and inverse Compton (IC) emission mechanisms. Methods. During the radio-to-optical monitoring provided by the GASP-WEBT, AGILE observed the source with its two co-aligned imagers, the gamma-ray imaging detector (GRID) and the hard X-ray imager (SuperAGILE), which are sensitive in the 30 MeV-30 GeV and 18-60 keV energy bands, respectively. Results. In the period 1-16 March 2008, AGILE detected γ-ray emission from PKS 1510−089 at a significance level of 6.2-σ with an average flux over the entire period of (84 ± 17) × 10 −8 photons cm −2 s −1 for photon energies above 100 MeV. After a predefined satellite re-pointing, between 17 and 21 March 2008, AGILE detected the source at a significance level of 7.3-σ, with an average flux (E > 100 MeV) of (134 ± 29) × 10 −8 photons cm −2 s −1 and a peak level of (281 ± 68) × 10 −8 photons cm −2 s −1 with daily integration. During the observing period January-April 2008, the source also showed an intense and variable optical activity, with several flaring episodes and a significant increase in the flux was observed at millimetric frequencies. Moreover, in the X-ray band, the Swi f t/XRT observations seem to show a harder-when-brighter behavior of the source spectrum. Conclusions. The flat spectrum radio quasar PKS 1510−089 showed strong activity between January and April 2008, with episodes of rapid variability from radio to γ-ray energy bands, in particular with a rapid γ-ray flaring episode. The spectral energy distribution of mid-March 2008 is modeled with a homogeneous one-zone synchrotron self Compton (SSC) emission plus contributions from inverse Compton scattering of external photons from both the accretion disk and the broad line region. Indeed, some features in the optical-UV spectrum seem to indicate Seyfert-like components such as the little and the big blue bumps.

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“…For details of the analysis of data from the Medicina and Noto radio observatories at those frequencies, see Bach et al (2007). As already apparent in Figure 1, most of the data at frequencies below 37 GHz were not well sampled on the P3 months timescale of the 2006 campaign, and any evidence for variability did not show a discernable correlation with the variability at higher (radio and optical) frequencies.…”

Section: Radio Observationsmentioning

confidence: 92%

The WEBT Campaign on the Blazar 3C 279 in 2006

Böttcher¹,

Basu²,

Joshi³

et al. 2007

ApJ

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The quasar 3C 279 was the target of an extensive multiwavelength monitoring campaign from 2006 January through April. An optical-IR-radio monitoring campaign by the Whole Earth Blazar Telescope (WEBT) collaboration was organized around target-of-opportunity X-ray and soft -ray observations with Chandra and INTEGRAL in 2006 midJanuary, with additional X-ray coverage by RXTE and Swift XRT. In this paper we focus on the results of the WEBT campaign. The source exhibited substantial variability of optical flux and spectral shape, with a characteristic timescale of a few days. The variability patterns throughout the optical BVRI bands were very closely correlated with each other, while there was no obvious correlation between the optical and radio variability. After the ToO trigger, the optical flux underwent a remarkably clean quasi-exponential decay by about 1 mag, with a decay timescale of d $ 12:8 days. In intriguing contrast to other (in particular, BL Lac type) blazars, we find a lag of shorter wavelength behind longer wavelength variability throughout the RVB wavelength ranges, with a time delay increasing with increasing frequency. Spectral hardening during flares appears delayed with respect to a rising optical flux. This, in combination with the very steep IR-optical continuum spectral index of 0 $ 1:5Y2:0, may indicate a highly oblique magnetic field configuration near the base of the jet, leading to inefficient particle acceleration and a very steep electron injection spectrum. An alternative explanation through a slow (timescale of several days) acceleration mechanism would require an unusually low magnetic field of B P 0:2 G, about an order of magnitude lower than inferred from previous analyses of simultaneous SEDs of 3C 279 and other flat-spectrum radio quasars with similar properties.

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Multi-frequency monitoring of γ-ray loud blazars

Cited by 38 publications

References 89 publications

Optical flux behaviour of a sample ofFermiblazars

Optical flux behaviour of a sample ofFermiblazars

AGILE detection of a rapid γ-ray flare from the blazar PKS 1510-089 during the GASP-WEBT monitoring

The WEBT Campaign on the Blazar 3C 279 in 2006

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