J/A+A/484/119 Multi-epoch VLBI survey of CJF sources (Britzen+, 2008)
A multi-epoch VLBI Survey of the kinematics of Caltech-Jodrell Bank flat-spectrum sources. Britzen S., Vermeulen R.C., Campbell R.M., Taylor G.B., Pearson T.J., Readhead A.C.S., Xu W., Browne I.W., Henstock D.R., Wilkinson P. <Astron. Astrophys. 484, 119 (2008)> =2008A&A...484..119B
ADC_Keywords: Active gal. nuclei ; BL Lac objects ; Galaxies, radio ; Radio sources ; VLBI Keywords: instrumentation: interferometers - galaxies: active - galaxies: quasars: general - galaxies: jets - galaxies: BL Lacertae objects: general Abstract: This is the second in a series of papers presenting VLBI observations of the 293 Caltech-Jodrell Bank Flat-spectrum (hereafter CJF) sources and their analysis. We obtain a consistent motion dataset large enough to allow the systematic properties of the population to be studied. We present detailed kinematic analysis of the complete flux-density limited CJF survey. We computed 2-D kinematic models based on the optimal model-fitting parameters of multi-epoch VLBA observations. This allows us to calculate not only radial, but also orthogonal motions, and thus to study curvature and acceleration. Statistical tests of the motions measured and their reliability were performed. A correlation analysis between the derived apparent motions, luminosities, spectral indices, and core dominance and the resulting consequences is described. With at least one velocity in each of the 237 sources, this sample is much larger than any available before, so it allows a meaning ful statistical investigation of apparent motions and any possible correlations with other parameters in AGN jets. The main results to emerge are as follows: * In general motions are not consistent with a single uniform velocity applicable to all components along a jet. * We find a slight trend towards a positive outward acceleration and also adduce some evidence for greater acceleration in the innermost regions. * We find a lack of fast components at physical distances less than a few pc from the reference feature. * Only ∼4% of the components from galaxies and <2% of those from quasars undergo large bends i.e. within 15° of ±90°. * The distribution of radial velocities shows a broad distribution of velocities (apparent velocities up to 30c). Fifteen percent of the best-sampled jet components exhibit low velocities that may need to be explained in a different manner to the fast motions. * Some negative superluminal motions are seen, and in 15 cases (6%) these are definitely significant. * We find a strong correlation between the 5 GHz luminosity and the apparent velocity. * The CJF galaxies, on average, show slower apparent jet-component velocities than the quasars. * The mean velocity in the VLBA 2cm survey (Kellermann et al. 2004) is substantially higher than in the CJF survey, the ratio could be roughly a factor of 1.5-2. This supports the observed trend toward increasing apparent velocity with in creasing observing frequency. This AGN survey provides the basis for any statistical analysis of jet and jet-component properties. Description: The results of the kinematic modeling for all 779 components from sources participating in the proper-motion analysis are listed. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file sources.dat 72 266 Source list tablec1.dat 188 779 The kinematic properties of 779 AGN-components fig/* 0 798 Kinematic modeling figures in PostScript
See also: J/A+A/472/763 : Multi-epoch VLBI survey of CJF sources (Britzen+, 2007) J/A+A/476/759 : X-ray properties of AGN from the CJF sample (Britzen+, 2007) Byte-by-byte Description of file: sources.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Name IAU-name of the source HHMM+DDd (B1950), CJF BHHMM+DDd in Simbad 10- 28 A19 --- Name2000 Name with J2000 position 31- 43 A13 ---- FileNameR Image name of pmtot, pmr and pmphi as function of radial distance from the core, in subdirectory fig 45- 57 A13 ---- FileNameT Image name x and y of each component as a function of time, in subdirectory fig (1) 59- 72 A14 ---- FileNameXY Image name of positions of all components at all epochs, in subdirectory fig (2)
Note (1): For each component, a "stationary" dotted line is plotted for reference. Note (2): The components are color-coded and the epochs are represented by different plotting symbols. The modeled positions at each epoch are shown in small black symbols.
Byte-by-byte Description of file: tablec1.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Name IAU-name of the source HHMM+DDd (B1950), CJF BHHMM+DDd in Simbad 10- 19 A10 --- Class Optical classification (1) 20- 21 A2 --- l_z [≥] Limit flag on z 22- 26 F5.3 --- z ? Redshift, see details in paper 27 A1 --- u_z [?] Uncertainty flag on z 29- 31 A3 --- Comp Jet-component identification (2) 33 I1 --- q [1/3] Quality class (3) 35 I1 --- NDet Number of times this component has been detected 37- 40 F4.2 yr Span Time span from the first to the last detection 42- 51 F10.4 d Epoch Reference epoch -2400000 53- 59 F7.3 mas X0 Component position at the reference epoch in rectangular X-coordinate 61- 65 F5.3 mas e_X0 ? rms uncertainty on X0 (4) 67- 73 F7.3 mas Y0 Component position at the reference epoch in rectangular Y-coordinate 75- 79 F5.3 mas e_Y0 ? rms uncertainty on Y0 (4) 81- 86 F6.3 mas/yr pmX Proper motion components in X 88- 92 F5.3 mas/yr e_pmX ? rms uncertainty on pmX (4) 94- 99 F6.3 mas/yr pmY Proper motion components in Y 101-105 F5.3 mas/yr e_pmY ? rms uncertainty on pmY (4) 107-112 F6.3 mas/yr pmr Radial proper motion component 114-118 F5.3 mas/yr e_pmr ? rms uncertainty on pmr (4) 120-125 F6.3 mas/yr pmphi Orthogonal proper motion component 127-131 F5.3 mas/yr e_pmphi ? rms uncertainty on pmphi (4) 133-137 F5.3 mas/yr pmtot Total proper motion, calculated from pmx, pmy 139-143 F5.3 mas/yr e_pmtot ? rms uncertainty on pmtot (4) 145-151 F7.3 c betar ? Radial apparent velocity 153-158 F6.3 c e_betar ? rms uncertainty on betar (4) 160-166 F7.3 c betaphi ? Orthogonal apparent velocity 168-173 F6.3 c e_betaphi ? rms uncertainty on betaphi (4) 175-181 F7.3 c betatot ? Total apparent velocity 183-188 F6.3 c e_betatot ? rms uncertainty on betatot (4)
Note (1): Optical classification as follows: Q = quasar B = BL Lac object G = galaxy U = unclassified Note (2): Jet-component identification as: C plus a number increasing with ordinal separation from the core CC in case of counter-jet denotes a counter-jet component Note (3): Quality flag is 1 for best to 3 for suffers from some problems in identification Note (4): Components that have observations at only two epochs do not have an associated uncertainty ; with no degrees of freedom in the fit for the kinematic model (four constraints and four unknowns), the scaling to ∼chi=1 is ill-defined.
Acknowledgements: Silke Britzen, sbritzen (at)mpifr-bonn.mpg.de
(End) Silke Britzen [MPIfR, Germany], Patricia Vannier [CDS] 09-Apr-2008
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