J/PASJ/73/313 Radio loudness and classification for radio source (Zhang+, 2021)
Radio loudness and classification for radio sources.
Zhang L., Fan J., Zhu J.
<Publ. Astron. Soc. Jap., 73, 313-325 (2021)>
=2021PASJ...73..313Z 2021PASJ...73..313Z (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; BL Lac objects ; QSOs
Keywords: galaxies: active - galaxies: jets - (galaxies:) quasars: general
Abstract:
The extragalactic radio sources are divided into two subclasses
(radio-loud and radio-quiet sources) in the literature using radio
loudness (R), which is defined as the ratio of radio emission to
optical emission, but the boundary R-value separating the two classes
is different in various sources. In this work, a sample of 2419
objects from the 13th catalog of quasars and active nuclei is used to
build a boundary for the two subclasses. To do so, we compiled the
radio and optical data, calculated their radio and optical indexes,
made K-correction, obtained the radio loudness, and adopted a Bayesian
analysis method to the logarithm of radio loudness for classification.
We also investigated the correlations of radio loudness with
radio/optical luminosities. Our main conclusions are summarized as
follows: (1) The distribution of the logarithm of radio loudness (log
R) is bimodal, the sources with log R<1.26 are classified as
radio-quiet sources, and those with log R>1.26 are classified as
radio-loud ones from the Bayesian analysis method. (2) The average
radio-optical effective spectral index of radio-quiet sources is
=0.05, while that of radio-loud sources is <αRO≥0.55. (3)
There are positive correlations between radio luminosity and radio
loudness for both radio-loud sources and radio-quiet sources. (4) A
dividing line of separating the distribution of the clusters on the
diagram of radio loudness against radio luminosity was obtained
statistically to set the boundary between radio-loud sources and
radio-quiet sources, with an accuracy of 99.73% based on the
classification result from the Bayesian analysis method.
Description:
In this work, we compiled a sample of 2419 radio sources with two
available radio flux densities, optical magnitudes from a catalogue of
quasars and active nuclei of the 13th edition (Veron-Cetty & Veron
2010A&A...518A..10V 2010A&A...518A..10V, Cat. VII/258), and J, H, and K magnitudes by
cross-matching the sources from 2MASS, and made corrections for the
dust reddening/absorption of the Galaxy. We calculated the radio
spectral index, the optical spectral index, the effective
radio-optical spectral index, and the radio loudness for our sample.
Then we adopted the Bayesian analysis method to study the
classification based on the distribution of the logarithm of radio
loudness, and investigated some correlations with radio loudness.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 139 2419 Samples
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See also:
VII/258 : Quasars and Active Galactic Nuclei (13th Ed.) (Veron+ 2010)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Name Source name
19- 24 F6.2 deg GLON ? Galactic longitude
26- 31 F6.2 deg GLAT ? Galactic latitude
33- 34 A2 --- CL [A BL Q] Type (1)
36- 39 F4.2 --- z ? Redshift
41- 45 F5.2 Jy F6 ? Radio flux density at 6cm
47- 51 F5.2 Jy F20 ? Radio flux density at 20cm
53- 57 F5.2 mag Vmag ? V magnitude
59- 63 F5.2 mag B-V ? B-V colour index
65- 69 F5.2 mag U-B ? U-B colour index
71- 76 F6.3 mag Jmag ? J magnitude
78- 83 F6.3 mag Hmag ? H magnitude
85- 90 F6.3 mag Kmag K magnitude
92- 96 F5.2 --- aR ? Radio spectral index, αR
98-102 F5.2 -- aO ? Optical spectral index, αO
104-107 F4.2 --- e_aO rms uncertainty on aO
109-113 F5.2 --- aRO Radio-optical effective spectral index,
αRO
115-119 F5.2 --- logR ? Radio loudness
121-124 F4.2 --- e_logR ? rms uncertainty on logR
126-130 F5.2 --- logLR ? Radio luminosity at 6cm
132-136 F5.2 --- logLO ? optical luminosity at the B band
138-139 A2 --- Mod [RL RQ] Classification mode from Bayesian
analysis method (2)
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Note (1): Type as follows:
A = AGN
BL = BL Lac object
Q = quasar
Note (2): Classification mode as follows:
RQ = radio-quiet sources
RL = radio-loud sources
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 18-Aug-2021