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The blazar sequence is a scenario in which the bolometric luminosity of the blazar governs the appearance of its spectral energy distribution. The most prominent result is the significant negative correlation between the synchrotron peak…

Astrophysics · Physics 2009-11-13 E. Nieppola , E. Valtaoja , M. Tornikoski , T. Hovatta , M. Kotiranta

Does the "blazar sequence" exist, or is it a result of a selection effect, due to the difficulty in measuring the redshifts of blazars with both high synchrotron peak frequencies (\gtrsim 10^{15} Hz) and luminosities (\gtrsim 10^{46} erg…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Justin Finke

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

The blazar sequence is reflected in a correlation of the peak luminosity versus peak frequency of the synchrotron component of blazars. This correlation has been considered one of the fundamental pieces of evidence for the existence of a…

High Energy Astrophysical Phenomena · Physics 2013-01-28 Justin D. Finke

Blazar population models have shown that the inverse-Compton and variability Doppler factor estimates yield consistent results at the population level for flat spectrum radio quasars (FSRQs). The two methods, however, are inconsistent when…

High Energy Astrophysical Phenomena · Physics 2017-06-28 I. Liodakis , A. Zezas , E. Angelakis , T. Hovatta , V. Pavlidou

Blazars are an extreme subclass of active galactic nuclei. Their rapid variability, luminous brightness, superluminal motion, and high and variable polarization are probably due to a beaming effect. However, this beaming factor (or Doppler…

High Energy Astrophysical Phenomena · Physics 2017-02-21 J. H. Fan , J. H. Yang , H. B. Xiao , C. Lin , D. Constantin , G. Y. Luo , Z. Y. Pei , J. M. Hao , Y. W. Mao

The blazar sequence, including negative correlations between radiative luminosity $L_{\rm rad}$ and synchrotron peak frequency $\nu$, and between Compton dominance $Y$ and $\nu$, is widely adopted as a phenomenological description of…

High Energy Astrophysical Phenomena · Physics 2024-02-16 Zhu-Jian Wan , Rui Xue , Ze-Rui Wang , Hu-Bing Xiao , Jun-Hui Fan

We compile 23 Gamma-ray Bursts (GRBs) and 21 blazars with estimated Doppler factors, and the Doppler factors of GRBs are estimated from their Lorentz factors by assuming their jet viewing angles \theta->0 degree. Using the conventional…

High Energy Astrophysical Phenomena · Physics 2015-05-30 Qingwen Wu , Yuan-Chuan Zou , Xinwu Cao , Ding-Xiong Wang , Liang Chen

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

Based on a large Fermi blazar sample, the blazar sequence (synchrotron peak frequency $\nu_{\rm peak}$ versus synchrotron peak luminosity $L_{\rm peak}$) is revisited. It is found that there is significant anti-correlation between $\nu_{\rm…

High Energy Astrophysical Phenomena · Physics 2015-05-07 Dingrong Xiong , Xiong Zhang , Jinming Bai , Haojing Zhang

Blazars are a subclass of active galactic nuclei (AGNs) with extreme observation properties, which is caused by the beaming effect, expressed by a Doppler factor, in a relativistic jet. Doppler factor is an important parameter in the…

High Energy Astrophysical Phenomena · Physics 2020-10-21 Zhiyuan Pei , Junhui Fan , Jianghe Yang , Denis Bastieri

Beaming effect is important for the observational properties of blazars. In this work, we collect 91 $Fermi$ blazars with available radio Doppler factors. $\gamma$-ray Doppler factors are estimated and compared with radio Doppler factors…

High Energy Astrophysical Phenomena · Physics 2017-07-19 C. Lin , J. H. Fan , H. B. Xiao

The kinetic energy of bulk relativistic plasma ejected from the central engine of blazars is converted into nonthermal particle energy in the comoving frame through a process of sweeping up material from the surrounding medium. The…

Astrophysics · Physics 2009-10-31 Charles D. Dermer

The Doppler factor ($\delta$) is a fundamental quality for the relativistic jets from active galactic nuclei (AGNs). It is also fundamental to assessing the number of the entire population of the jetted AGN at high redshift ($z$), and…

High Energy Astrophysical Phenomena · Physics 2025-01-28 Dahai Yan , Haiyun Zhang , Jianeng Zhou , Lijuan Dong

We present EVN observations of seven BL Lac objects selected from the RGB sample. To investigate the intrinsic radiation property of BL Lac objects, we estimated the Doppler factor with the VLA or MERLIN core and the total 408 MHz…

Astrophysics · Physics 2009-11-13 Zhongzu Wu , D. R. Jiang , Minfeng Gu , Yi Liu

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

Blazar radiation is dominated by a relativistic jet which can be modeled at first approximation using just two intrinsic parameters - the Lorentz factor $\Gamma$ and the viewing angle $\theta$. Blazar jet observations are often beamed due…

High Energy Astrophysical Phenomena · Physics 2016-06-29 Payaswini Saikia , Elmar Körding , Heino Falcke

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

Blazar emission is dominated by non-thermal radiation from a relativistic jet pointing toward us, therefore undergoing Doppler beaming. This is responsible for flux enhancement and contraction of the variability time scales, so that most…

High Energy Astrophysical Phenomena · Physics 2019-08-13 C. M. Raiteri , M. Villata

Blazars are among the most powerful extragalactic objects, as a sub-class of active galactic nuclei. They launch relativistic jets and their emitted radiation shows strong variability across the entire electro-magnetic spectrum. The…

High Energy Astrophysical Phenomena · Physics 2015-08-12 C. M. Fromm , L. Fuhrmann , M. Perucho
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