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  1. OA@INAF
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  3. 1 CONTRIBUTI IN RIVISTE (Journal articles)
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Please use this identifier to cite or link to this item: http://hdl.handle.net/20.500.12386/29561
Title: Radio loudness along the quasar main sequence
Authors: Ganci, V.
MARZIANI, Paola 
D'Onofrio, M.
del Olmo, A.
Bon, E.
Bon, N.
Negrete, C. A.
Issue Date: 2019
Journal: ASTRONOMY & ASTROPHYSICS 
Number: 630
First Page: A110
Abstract: Context. When can an active galactic nucleus (AGN) be considered radio loud (RL)? Following the established view of the AGNs inner workings, an AGN is RL if associated with relativistic ejections emitting a radio synchrotron spectrum (i.e., it is a "jetted" AGN). In this paper we exploit the AGN main sequence that offers a powerful tool to contextualize radio properties. <BR /> Aims: If large samples of optically-selected quasars are considered, AGNs are identified as RL if their Kellermann's radio loudness ratio R<SUB>K</SUB> > 10. Our aims are to characterize the optical properties of different classes based on radio loudness within the main sequence and to test whether the condition R<SUB>K</SUB> > 10 is sufficient for the identification of RL AGNs, since the origin of relatively strong radio emission may not be necessarily due to relativistic ejection. <BR /> Methods: A sample of 355 quasars was selected by cross-correlating the Very Large Array Faint Images of the Radio Sky at Twenty-Centimeters survey (FIRST) with the twelfth release of the Sloan Digital Sky Survey Quasar Catalog published in 2017. We classified the optical spectra according to their spectral types along the main sequence of quasars. For each spectral type, we distinguished compact and extended morphology (providing a FIRST-based atlas of radio maps in the latter case), and three classes of radio loudness: detected ( specific flux ratio in the g band and at 1.4 GHz, R'<SUB>K</SUB> < 10), intermediate (10 ≤ R'<SUB>K</SUB> < 70), and RL (R'<SUB>K</SUB> ≥ 70). <BR /> Results: The analysis revealed systematic differences between radio-detected (i.e., radio-quiet), radio-intermediate, and RL classes in each spectral type along the main sequence. We show that spectral bins that contain the extreme Population A sources have radio power compatible with emission by mechanisms ultimately due to star formation processes. RL sources of Population B are characteristically jetted. Their broad Hβ profiles can be interpreted as due to a binary broad-line region. We suggest that RL Population B sources should be preferential targets for the search of black hole binaries, and present a sample of binary black hole AGN candidates. <BR /> Conclusions: The validity of the Kellermann's criterion may be dependent on the source location along the quasar main sequence. The consideration of the main sequence trends allowed us to distinguish between sources whose radio emission mechanisms is jetted from the ones where the mechanism is likely to be fundamentally different. <P />Tables A.1-A.3 are only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/630/A110">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/630/A110</A>
URI: http://hdl.handle.net/20.500.12386/29561
URL: https://www.aanda.org/articles/aa/abs/2019/10/aa36270-19/aa36270-19.html
https://arxiv.org/abs/1908.07308
ISSN: 0004-6361
DOI: 10.1051/0004-6361/201936270
Bibcode ADS: 2019A&A...630A.110G
Fulltext: open
Appears in Collections:1.01 Articoli in rivista

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