J/ApJ/766/37 Sizes of MRC radio galaxies and QSOs (Singal+, 2013)
Unification scheme of radio galaxies and quasars falsified by their observed
size distributions.
Singal A.K., Singh R.L.
<Astrophys. J., 766, 37 (2013)>
=2013ApJ...766...37S 2013ApJ...766...37S
ADC_Keywords: Active gal. nuclei ; QSOs ; Redshifts ; Radio continuum
Keywords: galaxies: active; galaxies: nuclei; quasars: general;
radio continuum: general
Abstract:
In the currently popular orientation-based unified scheme, a radio
galaxy appears as a quasar when its principal radio-axis happens to be
oriented within a certain cone opening angle around the observer's
line of sight. Due to geometrical projection, the observed sizes of
quasars should therefore appear smaller than those of radio galaxies.
We show that this simple, unambiguous prediction of the unified scheme
is not borne out by the actually observed angular sizes of radio
galaxies and quasars. Except in the original 3CR sample, based on
which the unified scheme was proposed, in other much larger samples no
statistically significant difference is apparent in the size
distributions of radio galaxies and quasars. The population of
low-excitation radio galaxies with apparently no hidden quasars
inside, which might explain the observed excess number of radio
galaxies at low redshifts, cannot account for the absence of any
foreshortening of the sizes of quasars at large redshifts. On the
other hand, from infrared and X-ray studies, there is evidence of a
hidden quasar within a dusty torus in many radio galaxies, at z>0.5.
It is difficult to reconcile this with the absence of foreshortening
of quasar sizes at even these redshifts, and perhaps one has to allow
that the major radio axis may not have anything to do with the optical
axis of the torus. Otherwise, to resolve the dichotomy of radio
galaxies and quasars, a scheme quite different from the present might
be required.
Description:
For our investigations we have chosen an essentially complete MRC
sample (Kapahi et al. 1998ApJS..118..327K 1998ApJS..118..327K, 1998ApJS..118..275K 1998ApJS..118..275K), which
is about a factor of ∼5 deeper than the 3CR sample and has the
required radio and optical information. Optical spectroscopic data for
quasars with full observational details are given in Baker et al.
(1999ApJS..122...29B 1999ApJS..122...29B) with tabulations of redshifts, continuum, and
emission-line data for each source.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 47 494 Radio and optical data for our sample
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See also:
VIII/16 : Molonglo Reference Catalogue (MRC) of Radio Sources (Large+ 1991)
VIII/1 : The 3C and 3CR Catalogues (Edge+ 1959-1962)
J/AJ/148/16 : Updated 3CRR sample of radio sources (Singal, 2014)
J/ApJS/177/148 : 3CR radio source counterparts HST survey. II. (Floyd+, 2008)
J/AJ/130/23 : Spectrophotometry of 3CR lobe-dominated quasars (Aars+, 2005)
J/ApJS/107/19 : MRC/1Jy Radio source survey. I. (McCarthy+ 1996)
J/A+A/303/420 : Radio galaxies and quasars (Chyzy+, 1995)
J/MNRAS/204/151 : Bright radio sources at 178 MHz (3CRR) (Laing+ 1983)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1 A1 --- --- [B]
2- 9 A8 --- MRC MRC source name ( in Simbad)
12- 17 F6.3 Jy S408 [0.9/28.1] Flux density at 408MHz
19- 22 F4.2 --- alpha [0.5/1.6]? Spectral index;
S∝ν-α
24 A1 --- OT [GQU] Nature of optical object: G=Galaxy,
Q=Quasar, U=Unidentified
26- 30 F5.3 --- z [0.03/3.2]? Redshift when available
32- 37 F6.2 arcsec theta [0.9/372]? Largest angular size θ
39- 42 I4 kpc Size [3/1202]? Linear size
44- 47 E4.1 W/Hz P408 ? The 408MHz spectral luminosity
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 12-Nov-2014