The TANAMI Multiwavelength Program: Dynamic spectral energy distributions of southern blazars

Krauß F, Wilms J, Kadler M, Ojha R, Schulz R, Truestedt J, Edwards PG, Stevens J, Ros E, Baumgartner W, Beuchert T, Blanchard J, Buson S, Carpenter B, Dauser T, Falkner S, Gehrels N, Gräfe C, Gulyaev S, Hase H, Horiuchi S, Kreikenbohm A, Kreykenbohm I, Langejahn M, Leiter K, Lovell JEJ, Mueller C, Natusch T, Nesci R, Pursimo T, Phillips C, Ploetz C, Quick J, Tzioumis AK, Weston S (2016)

Publication Status: Published

Publication Type: Journal article, Original article

Publication year: 2016

Journal

Publisher: EDP Sciences

Book Volume: 591

Article Number: A130

DOI: 10.1051/0004-6361/201628595

Abstract

Context. Simultaneous broadband spectral and temporal studies of blazars are an important tool for investigating active galactic nuclei (AGN) jet physics. Aims. We study the spectral evolution between quiescent and flaring periods of 22 radio-loud AGN through multiepoch, quasi-simultaneous broadband spectra. For many of these sources these are the first broadband studies. Methods. We use a Bayesian block analysis of Fermi/LAT light curves to determine time ranges of constant flux for constructing quasi-simultaneous spectral energy distributions (SEDs). The shapes of the resulting 81 SEDs are described by two logarithmic parabolas and a blackbody spectrum where needed. Results. The peak frequencies and luminosities agree well with the blazar sequence for low states with higher luminosity implying lower peak frequencies. This is not true for sources in high states. The γ-ray photon index in Fermi/LAT correlates with the synchrotron peak frequency in low and intermediate states. No correlation is present in high states. The black hole mass cannot be determined from the SEDs. Surprisingly, the thermal excess often found in FSRQs at optical/UV wavelengths can be described by blackbody emission and not an accretion disk spectrum. Conclusions. The so-called harder-when-brighter trend, typically seen in X-ray spectra of flaring blazars, is visible in the blazar sequence. Our results for low and intermediate states, as well as the Compton dominance, are in agreement with previous results. Black hole mass estimates using recently published parameters are in agreement with some of the more direct measurements. For two sources, estimates disagree by more than four orders of magnitude, possibly owing to boosting effects. The shapes of the thermal excess seen predominantly in flat spectrum radio quasars are inconsistent with a direct accretion disk origin.

Authors with CRIS profile

Involved external institutions

Catholic University of America United States (USA) (US) Max-Planck-Institut für Radioastronomie / Max Planck Institute for Radio Astronomy Germany (DE) Commonwealth Scientific and Industrial Research Organisation (CSIRO) Australia (AU) National Aeronautics and Space Administration (NASA) United States (USA) (US) Auckland University of Technology / Te Wānanga Aronui o Tāmaki Makau Rau New Zealand (NZ) National Institute for Astrophysics / Istituto Nazionale Astrofisica (INAF) Italy (IT) Nordic Optical Telescope Spain (ES) Hartebeesthoek Radio Astronomy Observatory (HartRAO) South Africa (ZA) Julius-Maximilians-Universität Würzburg Germany (DE) Radboud University Nijmegen Netherlands (NL) University of Tasmania (UTAS) Australia (AU) Bundesamt für Kartographie und Geodäsie (BKG) / Federal Agency for Cartography and Geodesy Germany (DE) Universidad de Concepcion Chile (CL)

How to cite

APA:

Krauß, F., Wilms, J., Kadler, M., Ojha, R., Schulz, R., Truestedt, J.,... Weston, S. (2016). The TANAMI Multiwavelength Program: Dynamic spectral energy distributions of southern blazars. Astronomy & Astrophysics, 591. https://doi.org/10.1051/0004-6361/201628595

MLA:

Krauß, Felicia, et al. "The TANAMI Multiwavelength Program: Dynamic spectral energy distributions of southern blazars." Astronomy & Astrophysics 591 (2016).

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