Multi-Wavelength Variability Properties of Fermi Blazar S5 0716+714

Abstract

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, nearinfrared, 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 are 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, 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 nature 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. Leptonic model can explain this variability phenomenon through simultaneous SED modeling. Different leptonic models are distinguished by average SED modeling. The synchrotron plus synchrotron self-Compton (SSC) model is ruled out due to 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.

The Extreme Gamma-Ray Blazar S5 0716+714: Jet Conditions from Radio-Band Variability and Radiative Transfer Modeling

“…Cross-correlations of the fluxes from ground-based and satellite instruments at a variety of wavebands have been carried out for segments of the data sets in a number of recent papers, e.g. [9], and characteristic time scales identified using structure functions and periodograms [10]. This work identifies complex relationships which are overall consistent with the production of flaring by a common disturbance which propagates outward in the jet with time.…”

Investigating the Innermost Jet Structures of Blazar S5 0716+714 Using Uniquely Dense Intra-day Photo-polarimetric Observations

“…The X-ray spectrum of the continuum emission appears to have a concave shape, displaying a transition from the synchrotron to the inverse-Compton emission components (see e.g., [9,10]). S5 0716+714 has also been detected by γ-ray instruments such as the Compton EGRET, AGILE, Fermi-LAT satellites and also by the MAGIC Cherenkov telescope (see, e.g., [11][12][13][14] and references therein). In particular, there have been numerous optical microvariability studies of S5 0716+714 which reported many interesting results, including achromatic behavior, red noise-type power spectra, and in some cases, correlation between flux and polarization degree [15][16][17][18].…”