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Constraining the Limiting Brightness Temperature and Doppler Factors for the Largest Sample of Radio-bright Blazars

Liodakis, Ioannis and Hovatta, Talvikki and Huppenkothen, Daniela and Kiehlmann, Sebastian and Max-Moerbeck, Walter and Readhead, Anthony C. S. (2018) Constraining the Limiting Brightness Temperature and Doppler Factors for the Largest Sample of Radio-bright Blazars. Astrophysical Journal, 866 (2). Art. No. 137. ISSN 1538-4357. doi:10.3847/1538-4357/aae2b7.

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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 describe the blazar populations best. We use a Bayesian hierarchical code called {\it Magnetron} to model the light curves of 1029 sources observed by the Owens Valley Radio Observatory's 40-m telescope as a series of flares with an exponential rise and decay, and estimate their variability brightness temperature. Our analysis allows us to place the most stringent constraints on the equipartition brightness temperature i.e., the maximum achieved intrinsic brightness temperature in beamed sources which we found to be ⟨T_(eq)⟩=2.78 × 10^(11) K ± 26%. Using our findings we estimated the variability Doppler factor for the largest sample of blazars increasing the number of available estimates in the literature by almost an order of magnitude. Our results clearly show that γ-ray loud sources have faster and higher amplitude flares than γ-ray quiet sources. As a consequence they show higher variability brightness temperatures and thus are more relativistically beamed, with all of the above suggesting a strong connection between the radio flaring properties of the jet and γ-ray emission.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Liodakis, Ioannis0000-0001-9200-4006
Hovatta, Talvikki0000-0002-2024-8199
Huppenkothen, Daniela0000-0002-1169-7486
Kiehlmann, Sebastian0000-0001-6314-9177
Max-Moerbeck, Walter0000-0002-5491-5244
Readhead, Anthony C. S.0000-0001-9152-961X
Additional Information:© 2018 The American Astronomical Society. Received 2018 June 5; revised 2018 September 7; accepted 2018 September 16; published 2018 October 23. We thank the anonymous referee for comments and suggestions that helped improve this work. This research has made use of data from the OVRO 40 m monitoring program (Richards et al. 2011), which is supported in part by NASA grants NNX08AW31G, NNX11A043G, and NNX14AQ89G and NSF grants AST-0808050 and AST-1109911. This research has made use of data from the MOJAVE database, which is maintained by the MOJAVE team (Lister et al. 2018). This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France (Wenger et al. 2000). This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Facility: OVRO. - Software: Magnetron (Huppenkothen et al. 2015), DNest4 (Brewer & Foreman-Mackey 2016), Numpy (Van Der Walt et al. 2011), Scipy (Jones et al. 2001).
Group:Astronomy Department
Funding AgencyGrant Number
Subject Keywords:galaxies: active – galaxies: jets – relativistic processes
Issue or Number:2
Record Number:CaltechAUTHORS:20181023-124341266
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Official Citation:Ioannis Liodakis et al 2018 ApJ 866 137
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:90367
Deposited By: Tony Diaz
Deposited On:23 Oct 2018 19:53
Last Modified:16 Nov 2021 03:32

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