Observations of six flat spectrum sources from the 5 GHz survey

Biermann, Peter L.; Duerbeck, H. W.; Eckart, A.; Fricke, K. J.; Johnston, K. J.; Kühr, H.; Liebert, J.; Pauliny-Toth, I. I. K.; Schleicher, H.; Stockman, H. S.; Strittmatter, P. A.; Witzel, A.

doi:10.1086/183588

Cited by 79 publications

(50 citation statements)

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“…It was discovered in the Bonn-NRAO radio survey (Kühr et al 1981) and was identified as a BL Lac object (Biermann et al 1981). The source was classified as a LBL (Padovani & Giommi 1995) or an intermediate synchrotron peaked (Abdo et al 2010a) blazar.…”

Section: Historical Observations Of S5 0716+714mentioning

confidence: 99%

MULTIWAVELENGTH VARIABILITY PROPERTIES OFFERMIBLAZAR S5 0716+714

Liao

Bai

Liu

et al. 2014

ApJ

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S5 0716+714 is a typical BL Lacertae object. In this paper we present the analysis and results of long-term simultaneous observations in the radio, near-infrared, optical, X-ray, and γ -ray bands, together with our own photometric observations for this source. The light curves show that the variability amplitudes in γ -ray and optical bands are larger than those in the hard X-ray and radio bands and that the spectral energy distribution (SED) peaks move to shorter wavelengths when the source becomes brighter, which is similar to other blazars, i.e., more variable at wavelengths shorter than the SED peak frequencies. Analysis shows that the characteristic variability timescales in the 14.5 GHz, the optical, the X-ray, and the γ -ray bands are comparable to each other. The variations of the hard X-ray and 14.5 GHz emissions are correlated with zero lag, and so are the V band and γ -ray variations, which are consistent with the leptonic models. Coincidences of γ -ray and optical flares with a dramatic change of the optical polarization are detected. Hadronic models do not have the same natural explanation for these observations as the leptonic models. A strong optical flare correlating a γ -ray flare whose peak flux is lower than the average flux is detected. The leptonic model can explain this variability phenomenon through simultaneous SED modeling. Different leptonic models are distinguished by average SED modeling. The synchrotron plus synchrotron selfCompton (SSC) model is ruled out because of the extreme input parameters. Scattering of external seed photons, such as the hot-dust or broad-line region emission, and the SSC process are probably both needed to explain the γ -ray emission of S5 0716+714.

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Section: Historical Observations Of S5 0716+714mentioning

confidence: 99%

MULTIWAVELENGTH VARIABILITY PROPERTIES OFFERMIBLAZAR S5 0716+714

Liao

Bai

Liu

et al. 2014

ApJ

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“…Two years later, it was classified as a BL Lac (Biermann et al 1981) because of its featureless optical spectrum and high linear polarization. The optical continuum was so featureless that every attempt to determine its spectroscopic redshift has failed.…”

Section: Introductionmentioning

confidence: 99%

AGILE detection of variable γ-ray activity from the blazar S5 0716+714 in September–October 2007

Chen¹,

D’Ammando

Villata

et al. 2008

A&A

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Aims. We report the γ-ray activity from the intermediate BL Lac S5 0716+714 during observations acquired by the AGILE satellite in September and October 2007. These detections of activity were contemporaneous with a period of intense optical activity, which was monitored by GASP-WEBT. This simultaneous optical and γ-ray coverage allows us to study in detail the light curves, time lags, γ-ray photon spectrum, and Spectral Energy Distributions (SEDs) during different states of activity. Methods. AGILE observed the source with its two co-aligned imagers, the Gamma-Ray Imaging Detector (GRID) and the hard X-ray imager (Super-AGILE), which are sensitive to the 30 MeV-50 GeV and 18-60 keV energy ranges, respectively. Observations were completed in two different periods, the first between 2007 September 4-23, and the second between 2007 October 24-November 1. Results. Over the period 2007 September 7-12, AGILE detected γ-ray emission from the source at a significance level of 9.6-σ with an average flux (E > 100 MeV) of (97 ± 15) × 10 −8 photons cm −2 s −1 , which increased by a factor of at least four within three days. No emission was detected by Super-AGILE for the energy range 18-60 keV to a 3-σ upper limit of 10 mCrab in 335 ks. In October 2007, AGILE repointed toward S5 0716+714 following an intense optical flare, measuring an average flux of (47 ± 11) × 10 −8 photons cm −2 s −1 at a significance level of 6.0-σ. Conclusions. The γ-ray flux of S5 0716+714 detected by AGILE is the highest ever detected for this blazar and one of the most intense γ-ray fluxes detected from a BL Lac object. The SED of mid-September appears to be consistent with the synchrotron self-Compton (SSC) emission model, but only by including two SSC components of different variabilities.

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“…The superluminal radio source 2007+777 (Witzel et al, 1988) was identified as a BL Lac object owing to its almost featureless optical spectrum (Biermann et al, 1981). It recently showed rapid variations on time scales of days at optical, infrared and radio wavelengths (Peng et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

“…It recently showed rapid variations on time scales of days at optical, infrared and radio wavelengths (Peng et al, 2000). Flux density measurements with the 100 m radio telescope at Effelsberg show that 2007+777 belongs to the slower class of intraday variable radio sources (type I).…”

Section: Introductionmentioning

confidence: 99%

VSOP Observations of the BL Lac Object 2007+777

Jin

Krichbaum

Witzel

et al. 2001

International Astronomical Union Colloquium

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Abstract. We present three epochs of VSOP observations of the BL Lac object 2007+777 at 5 GHz. Compared with the ground-based VLBA data, the space baselines with HALCA clearly reveal a more detailed and finer source structure. Mainly based on the quite uniform and circular UV-coverages of the VLBA, and using a new cross-selfcalibration method, we have found evidence for weak structural changes on a timescale of two weeks in the core region of this intraday variable source. The physical causes for these variations are discussed.

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Observations of six flat spectrum sources from the 5 GHz survey

Cited by 79 publications

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MULTIWAVELENGTH VARIABILITY PROPERTIES OFFERMIBLAZAR S5 0716+714

MULTIWAVELENGTH VARIABILITY PROPERTIES OFFERMIBLAZAR S5 0716+714

AGILE detection of variable γ-ray activity from the blazar S5 0716+714 in September–October 2007

VSOP Observations of the BL Lac Object 2007+777

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