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Title: Constraining Emission Models of Luminous Blazar Sources

Abstract

Many luminous blazars which are associated with quasar-type active galactic nuclei display broad-band spectra characterized by a large luminosity ratio of their high-energy ({gamma}-ray) and low-energy (synchrotron) spectral components. This large ratio, reaching values up to 100, challenges the standard synchrotron self-Compton models by means of substantial departures from the minimum power condition. Luminous blazars have also typically very hard X-ray spectra, and those in turn seem to challenge hadronic scenarios for the high energy blazar emission. As shown in this paper, no such problems are faced by the models which involve Comptonization of radiation provided by a broad-line-region, or dusty molecular torus. The lack or weakness of bulk Compton and Klein-Nishina features indicated by the presently available data favors production of {gamma}-rays via up-scattering of infrared photons from hot dust. This implies that the blazar emission zone is located at parsec-scale distances from the nucleus, and as such is possibly associated with the extended, quasi-stationary reconfinement shocks formed in relativistic outflows. This scenario predicts characteristic timescales for flux changes in luminous blazars to be days/weeks, consistent with the variability patterns observed in such systems at infrared, optical and {gamma}-ray frequencies. We also propose that the parsec-scale blazar activity canmore » be occasionally accompanied by dissipative events taking place at sub-parsec distances and powered by internal shocks and/or reconnection of magnetic fields. These could account for the multiwavelength intra-day flares occasionally observed in powerful blazars sources.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
968513
Report Number(s):
SLAC-PUB-13770
Journal ID: ISSN 0004-637X; ASJOAB; arXiv:0904.1414; TRN: US0904682
DOE Contract Number:  
AC02-76SF00515
Resource Type:
Journal Article
Journal Name:
Astrophys.J.704:38-50,2009
Additional Journal Information:
Journal Volume: 704; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; LUMINOSITY; MAGNETIC FIELDS; NUCLEI; PHOTONS; PRODUCTION; RADIATIONS; SPECTRA; SYNCHROTRONS; X-RAY SPECTRA; Astrophysics,ASTRO

Citation Formats

Sikora, Marek, /Warsaw, Copernicus Astron. Ctr., Stawarz, Lukasz, /Kipac, Menlo Park /Jagiellonian U., Astron. Observ. /SLAC, Moderski, Rafal, Nalewajko, Krzysztof, /Warsaw, Copernicus Astron. Ctr., Madejski, Greg, and /KIPAC, Menlo Park /SLAC. Constraining Emission Models of Luminous Blazar Sources. United States: N. p., 2009. Web. doi:10.1088/0004-637X/704/1/38.
Sikora, Marek, /Warsaw, Copernicus Astron. Ctr., Stawarz, Lukasz, /Kipac, Menlo Park /Jagiellonian U., Astron. Observ. /SLAC, Moderski, Rafal, Nalewajko, Krzysztof, /Warsaw, Copernicus Astron. Ctr., Madejski, Greg, & /KIPAC, Menlo Park /SLAC. Constraining Emission Models of Luminous Blazar Sources. United States. https://doi.org/10.1088/0004-637X/704/1/38
Sikora, Marek, /Warsaw, Copernicus Astron. Ctr., Stawarz, Lukasz, /Kipac, Menlo Park /Jagiellonian U., Astron. Observ. /SLAC, Moderski, Rafal, Nalewajko, Krzysztof, /Warsaw, Copernicus Astron. Ctr., Madejski, Greg, and /KIPAC, Menlo Park /SLAC. 2009. "Constraining Emission Models of Luminous Blazar Sources". United States. https://doi.org/10.1088/0004-637X/704/1/38. https://www.osti.gov/servlets/purl/968513.
@article{osti_968513,
title = {Constraining Emission Models of Luminous Blazar Sources},
author = {Sikora, Marek and /Warsaw, Copernicus Astron. Ctr. and Stawarz, Lukasz and /Kipac, Menlo Park /Jagiellonian U., Astron. Observ. /SLAC and Moderski, Rafal and Nalewajko, Krzysztof and /Warsaw, Copernicus Astron. Ctr. and Madejski, Greg and /KIPAC, Menlo Park /SLAC},
abstractNote = {Many luminous blazars which are associated with quasar-type active galactic nuclei display broad-band spectra characterized by a large luminosity ratio of their high-energy ({gamma}-ray) and low-energy (synchrotron) spectral components. This large ratio, reaching values up to 100, challenges the standard synchrotron self-Compton models by means of substantial departures from the minimum power condition. Luminous blazars have also typically very hard X-ray spectra, and those in turn seem to challenge hadronic scenarios for the high energy blazar emission. As shown in this paper, no such problems are faced by the models which involve Comptonization of radiation provided by a broad-line-region, or dusty molecular torus. The lack or weakness of bulk Compton and Klein-Nishina features indicated by the presently available data favors production of {gamma}-rays via up-scattering of infrared photons from hot dust. This implies that the blazar emission zone is located at parsec-scale distances from the nucleus, and as such is possibly associated with the extended, quasi-stationary reconfinement shocks formed in relativistic outflows. This scenario predicts characteristic timescales for flux changes in luminous blazars to be days/weeks, consistent with the variability patterns observed in such systems at infrared, optical and {gamma}-ray frequencies. We also propose that the parsec-scale blazar activity can be occasionally accompanied by dissipative events taking place at sub-parsec distances and powered by internal shocks and/or reconnection of magnetic fields. These could account for the multiwavelength intra-day flares occasionally observed in powerful blazars sources.},
doi = {10.1088/0004-637X/704/1/38},
url = {https://www.osti.gov/biblio/968513}, journal = {Astrophys.J.704:38-50,2009},
issn = {0004-637X},
number = ,
volume = 704,
place = {United States},
year = {Fri Oct 30 00:00:00 EDT 2009},
month = {Fri Oct 30 00:00:00 EDT 2009}
}