J/AZh/85/314 Complete sample of flat-spectrum radio sources (Gorshkov+, 2008)
Long-term variability of a complete sample of flat-spectrum radio sources at
declinations of 4°-6° (B1950).
Gorshkov A.G., Konnikova V.K., Mingaliev M.G.
<Astron. Zh. 85, 314 (2008)>
=2008AZh....85..314G 2008AZh....85..314G
=2008ARep...52..278G 2008ARep...52..278G
ADC_Keywords: Radio sources
Abstract:
We present the results of twenty-year observations of a complete
sample of 68 flat-spectrum radio sources with flux densities
S3.9GHz>200mJy carried out at centimeter wavelengths with the RATAN-600
radio telescope. Since 1995, we have observed simultaneously at six
frequencies between 0.97 and 21.7GHz. Of the 56 sources identified
with optical objects, 41 are quasars with redshifts between 0.293 and
3.263. Based on our analysis of the spectral shapes, we divide the
sources into four classes. Changes of spectral class for individual
sources are fairly rare. Based on the light curves and spectra, in
most cases,a flare's evolution is in accordance with a model in which
the variations result from the evolution of a shock in the radio jet.
The main result of our study is that there is no redshift dependence
for the true linear sizes of the radiating regions, the variability
indices derived for all 20 years of data or for individual flares, or
the peak frequencies of the spectra of the compact radio emission. We
suggest that this testifies to an absence of cosmological evolution of
the sample quasars, at least to z∼3.
Description:
We observed the flat-spectrum radio sources in our sample in April and
September 1984, September 1985, May and July 1987, July and December
1988, March 1989, August and September 1990, August and December 1991,
and February-March 1992 at 3.9 and 7.7GHz (on some runs, also at
7.5GHz), using the southern sector of the RATAN-600 with the
telescope's periscope. The sources were also observed on the northern
sector of the RATAN-600 at 4.85 and 11.1 GHz in August 1990.
In 1995, after a break due to renovation of the telescope, we continued
simultaneous observations at 0.97, 2.3, 3.9, 7.7, 11.1, and 21.7GHz.
Observations were performed on the western sector of the telescope at
an azimuth of 270° in October 1996 and April 1997, and on the
northern sector in April and November 1995, July 1996, and May,
August, and November 1997, with some sources being observed on the
southern sector with the periscope. Sources were observed daily, in
series covering from 10 to 30 days. Beginning in 1998, we obtained
long series of observations covering from 60 to 100 days.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 80 68 Coordinates, identifications, and variability
amplitudes of the sources
table2.dat 59 43 Parameters of sources derived from the
long-term flux-density variations
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See also:
VIII/60 : Interferometer phase calibration sources (Patnaik+ 1998)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Name (JHHMM+DDMM)
12- 13 I2 h RAh Right ascension (J2000) (1)
15- 16 I2 min RAm Right ascension (J2000) (1)
18- 23 F6.3 s RAs Right ascension (J2000) (1)
25 A1 --- DE- Declination sign (J2000) (1)
26- 27 I2 deg DEd Declination (J2000) (1)
29- 30 I2 arcmin DEm Declination (J2000) (1)
32- 36 F5.2 arcsec DEs Declination (J2000) (1)
38- 40 A3 --- Cl Classification (G1)
42- 46 F5.3 --- z ? Redshift
48- 51 F4.1 mag Bmag ? B magnitude (2)
53- 54 I2 --- r_z ? Reference for redshift (3)
56- 59 F4.2 --- V3.9 ? Variability index at 3.9GHz (4)
61 A1 --- --- [(]
62- 65 F4.2 --- V3.9c ? Variability index at 3.9GHz after
subtracting the extended component (4)
66 A1 --- --- [)]
68- 71 F4.2 --- V7.7 ? Variability index at 7.7GHz (4)
73 A1 --- --- [(]
74- 77 F4.2 --- V7.7c ? Variability index at 7.7GHz after
subtracting the extended component (4)
78 A1 --- --- [)]
80 I1 --- Sp [1/4] Spectrum class (5)
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Note (1): J2000 coordinates from the Jodrell Bank VLA Astrometric Survey
(JVAS) at 8.4GHz (Cat. VIII/60) or the NRAO VLA Sky Survey (NVSS) at
1.4GHz (Cat. VIII/65).
Note (2): Magnitude from USNO-A1.0 (1996, see Cat. I/284) or APM
(1993PASP..105..521P 1993PASP..105..521P) astrometric surveys.
Note (3): References for redshift as follows:
29 = Veron-Cetty and Veron, 2003A&A...412..399V 2003A&A...412..399V, See Cat. VII/248
19 = Richards et al., Cat. J/AJ/131/2766
20 = NED database, http://nedwww.ipac.caltech.edu
21 = Gorshkov and Konnikova, 1993PAZh...19..136G 1993PAZh...19..136G
22 = Chavushyan et al., 2000AstL...26..339C 2000AstL...26..339C
23 = Chavushyan et al., 2001ARep...45...79C 2001ARep...45...79C
24 = Afanas'ev et al., 2003ARep...47..377A 2003ARep...47..377A
25 = Afanas'ev et al., 2006ARep...50..255A 2006ARep...50..255A
Note (4): The variability index is defined as
V=[(Smax-eSmax)-(Smin+eSmin)]/[(Smax-eSmax)+(Smin+eSmin)]
where Smax and Smin are the highest and lowest flux densities recorded
in the 20 years and e_Smax and e_Smin are the rms errors.
Note (5): Spectrum class as follows:
1 = single-component spectrum
2 = two-component stpectrum
3 = spectrum with a dominant extended component
4 = complex spectrum
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Object name
11 A1 --- n_Name [*] * when no intermediate observations between
the minimum and the level assumed to be
the flare maximum
13- 14 A2 --- Cl Classification (G1)
16- 20 F5.3 --- z ? Redshift
22- 25 F4.2 --- Vf 7.7-GHz flare variability index
27- 30 I4 mJy DS Flare amplitude (DS=Smax-Smin)
32- 35 F4.2 yr tau Flare timescale
37- 40 F4.2 pc R ? Apparent linear size
42- 47 F6.4 mas theta ? Apparent angular size
48- 54 F7.3 10+12K Tb ? Brightness temperature in the source
rest frame
56- 59 F4.2 --- Dvar ? Corresponding Doppler factor,
Dvar=(T0b/1012)1/3
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Global notes:
Note (G1): Classifications as follows:
Q = quasar
G = galaxy
EmG = emission-line galaxy
SyG = Seyfert galaxy
L = BL Lac object
EF = empty field
+ = identified but not yet classified
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 23-Jun-2008