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Blazars optical emission is generally dominated by relativistic jets, although the host galaxy, accretion disk and broad line region (BLR) may also contribute significantly. Disentangling their contributions has been challenging for years…

BeppoSAX is best known for its role in the disclosure of the Gamma-Ray Burst mystery, but it has also improved our understanding of jetted sources in general, and blazars in particular. On the interpretational side, we are curious to see if…

Astrophysics · Physics 2007-05-23 G. Ghisellini , A. Celotti

Blazars are highly variable active galactic nuclei which emit radiation at all wavelengths from radio to gamma-rays. Polarized radiation from blazars is one key piece of evidence for synchrotron radiation at low energies and it also varies…

We examine the fundamental plane of 91 Blazars which include FSRQs and BL Lacs with known X-ray luminosity ($L_{R}$), radio luminosity ($L_X$), and black hole mass measurements ($M$) to reflect the relationship between jet and accretion for…

High Energy Astrophysical Phenomena · Physics 2024-03-15 Xu Zhang , Dingrong Xiong , Quangui Gao , Guiqin Yang , Fangwu Lu , Weiwei Na , Longhua Qin

We determined the basic parameters, such as the central black hole mass ($M$), the boosting factor (or Doppler factor) ($\delta$), the propagation angle ($\Phi$) and the distance along the axis to the site of $\gamma$-ray production ($d$)…

Astrophysics · Physics 2009-11-10 J. H. Fan

Black holes, anywhere in the stellar-mass to supermassive range, are often associated with relativistic jets. Models suggest that jet production may be a universal process common in all black hole systems regardless of their mass. Although…

Relativistic effects dominate the emission of blazar jets complicating our understanding of their intrinsic properties. Although many methods have been proposed to account for them, the variability Doppler factor method has been shown to…

High Energy Astrophysical Phenomena · Physics 2018-10-31 I. Liodakis , T. Hovatta , D. Huppenkothen , S. Kiehlmann , W. Max-Moerbeck , A. C. S. Readhead

(Abridged) We analyze blazar jet apparent speeds and accelerations from the RDV series of astrometric and geodetic VLBI experiments. From these experiments, we have produced and analyzed 2753 global VLBI images of 68 sources at 8 GHz with a…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-20 B. G. Piner , A. B. Pushkarev , Y. Y. Kovalev , C. J. Marvin , J. G. Arenson , P. Charlot , A. L. Fey , A. Collioud , P. A. Voitsik

We estimate the power of relativistic, extragalactic jets by modelling the spectral energy distribution of a large number of blazars. We adopt a simple one-zone, homogeneous, leptonic synchrotron and inverse Compton model, taking into…

Astrophysics · Physics 2009-11-13 A. Celotti , G. Ghisellini

I show that by assuming a standard Blandford-Konigl jet, it is possible to determine the bulk Lorentz factor and angle to the line of sight of self-similar parsec-scale blazar jets by using five measured quantities: redshift, core radio…

Astrophysics of Galaxies · Physics 2019-01-09 Justin D. Finke

Blazars are a class of active galactic nuclei which host relativistic jets oriented close to the observer's line of sight. Blazars have very complex variability properties. Flares, namely flux variations around the mean value with a…

High Energy Astrophysical Phenomena · Physics 2022-01-19 Ze-Rui Wang , Ruo-Yu Liu , Maria Petropoulou , Foteini Oikonomou , Rui Xue , Xiang-Yu Wang

We had earlier shown that for a constant velocity jet the discrepancy between the low speeds indicated by VLBI knot motions and the high Doppler factors inferred from emission of TeV photons could be reconciled if ultrarelativistic jets…

Astrophysics · Physics 2007-07-25 Paul J. Wiita , Gopal-Krishna , Samir Dhurde , Pronoy Sircar

We have calculated variability Doppler boosting factors, Lorentz factors, and viewing angles for a large sample of sources by using total flux density observations at 22 and 37 GHz and VLBI data. We decomposed the flux curves into…

Astrophysics · Physics 2009-11-13 T. Hovatta , E. Valtaoja , M. Tornikoski , A. Lähteenmäki

In a companion paper we presented a statistical model for the blazar population, consisting of distributions for the unbeamed radio luminosity function and the Lorentz factor distribution of each of the BL Lac and Flat Spectrum Radio Quasar…

High Energy Astrophysical Phenomena · Physics 2015-10-21 I. Liodakis , V. Pavlidou

Blazars are a subclass of radio-loud active galactic nuclei (AGNs), where the jet is aligned close to the line of sight. Blazars emission is dominated by non-thermal processes, where Doppler boosted radiation originates from a relativistic…

High Energy Astrophysical Phenomena · Physics 2021-08-19 Jakub Juryšek , Vitalii Sliusar , Dimitri Moulin , Roland Walter

Blazars are a rare class of active galactic nuclei (AGN) with relativistic jets pointing towards the observer. Jets are thought to be launched as Poynting-flux dominated outflows that accelerate to relativistic speeds at the expense of the…

High Energy Astrophysical Phenomena · Physics 2022-11-16 Maria Petropoulou , Filippos Psarras , Dimitrios Giannios

The radiation we observe from blazars is most likely the product of the transformation of bulk kinetic energy into random energy. This process must have a relatively small efficiency (e.g. 10%) if jets are to power the extended…

Astrophysics · Physics 2009-10-31 G. Ghisellini

Gamma-ray bursts (GRBs) are powered by ultra-relativistic jets. Usually a minimum value of the Lorentz factor of the relativistic bulk motion is obtained based on the argument that the observed high energy photons ($\gg {\rm MeV}$) can…

High Energy Astrophysical Phenomena · Physics 2015-04-16 Qing-Wen Tang , Fang-Kun Peng , Xiang-Yu Wang , Pak-Hin Thomas Tam

The observed apparent velocities and luminosities of the relativistic jets in AGNs are significantly different from their intrinsic values due to strong special relativistic effects. We adopt the maximum likelihood method to determine…

Astrophysics · Physics 2009-11-13 Yuan Liu , Shuang Nan Zhang

Most of the electromagnetic output of blazars (BL Lac objects and Flat Spectrum Radio Quasars) comes out in the gamma-ray band, making the Large Area Telescope [0.1-100 GeV] onboard the Fermi satellite and the Cherenkov telescopes crucial…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 G. Ghisellini