J/A+A/651/A64 Position difference vectors and of the jets (Lambert+, 2021)
Parsec-scale alignments of radio-optical offsets with jets in AGNs from
multifrequency geodetic VLBI, Gaia EDR3, and the MOJAVE program.
Lambert S., Liu N., Arias E.F., Barache C., Souchay J., Taris F., Liu J.C.,
Zhu Z.
<Astron. Astrophys. 651, A64 (2021)>
=2021A&A...651A..64L 2021A&A...651A..64L (SIMBAD/NED BibCode)
ADC_Keywords: Positional data ; References ; Interferometry ; QSOs
Keywords: reference systems - quasars - technique: interferometry -
technique: Gaia
Abstract:
We aim to study the relative positions of quasar emission centers at
different wavelengths in order to help link the various realizations
of the International Celestial Reference System (ICRS), and to unveil
systematic uncertainties and individual source behavior at different
wavelengths.
We based our study on four catalogs representing the ICRS, the ICRF3
positions in the three VLBI bands X, K, and Ka, and the Gaia EDR3
catalog in optical wavelengths. We complemented radio source positions
with jet kinematics results from the MOJAVE team, allowing us to
obtain jet directions on the sky. A six-parameter deformation model
was used to remove systematic uncertainties present in the different
catalogs.
For a set of 194 objects common to the four catalogs and to the
objects whose jet kinematics was studied by the MOJAVE team, we
computed the orientation between positions at the different
wavelengths and with respect to the directions of the jets. We find
that the majority of these objects have their radio-to-optical vector
along the jet, with the optical centroid downstream from the radio
centroids, and that the K and Ka centroids are preferably upstream in
the jet with respect to the X centroid, which is consistent with the
paradigm of a simple core-jet model. For a population of
multiwavelength positions aligned along the jet, astrometric
information can therefore be used to measure the direction of the jet
independently of imaging. In addition, we find several sources for
which the optical centroid coincides with stationary radio features
with a relatively high fraction of polarization, indicating optical
emission dominated by a synchrotron process in the jet.
Description:
The file contains the length and orientation of the X-to-K, X-to-Ka,
and X-to-O difference vectors (as deduced from ICRF3 and Gaia EDR3
astrometry) and position angle of the jet as deduced from MOJAVE data.
Composite maps of intensity distribution together with X, K, Ka, and O
positions for the 194 sources common to MOJAVE, ICRF3, and Gaia EDR33.
The intensity distribution was obtained from the stacking of all
components provided by Lister et al. (2019, Cat. J/ApJ/874/43)
convoluted by a Gaussian circular beam of radius 0.1 mas. The contour
levels indicate the normalized amplitude 10-7, 10-6, 10-5,
10-4, 0.001, 0.01, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.
We set the X centroid onto the stationary component of Lister et al.
(2019, Cat. J/ApJ/874/43). The error ellipses in the maps represent
three times the error ellipse deduced from uncertainties in right
ascension and declination and their correlations as reported in the
ICRF3 and Gaia EDR3 catalogs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 95 194 Length and orientation of astrometric position
difference vectors and of the jets
img/* . 194 Individual png images
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See also:
J/ApJ/874/43 : MOJAVE XVII. Parsec-scale jet kinematics of AGNs (Lister+, 2019)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- IERS Radio source IERS designation
10- 14 F5.3 mas LXK Length of the X-to-K difference vector
16- 20 F5.3 mas e_LXK Uncertainty of the X-to-K difference vector
22- 24 I3 deg PXK Position angle of the X-to-K difference vector
26- 28 I3 deg e_PXK Uncertainty of the position angle of the
X-to-K difference vector
30- 34 F5.3 mas LXKa Length of the X-to-Ka difference vector
36- 40 F5.3 mas e_LXKa Uncertainty of the X-to-Ka difference vector
42- 44 I3 deg PXKa Position angle of the X-to-Ka difference vector
46- 48 I3 deg e_PXKa Uncertainty of the position angle of the
X-to-Ka difference vector
50- 55 F6.3 mas LXO Length of the X-to-O difference vector
57- 61 F5.3 mas e_LXO Uncertainty of the X-to-O difference vector
63- 65 I3 deg PXO Position angle of the X-to-O difference vector
67- 69 I3 deg e_PXO Uncertainty of the position angle of the
X-to-O difference vector
71- 73 I3 deg Pjet Position angle of the 15GHz radio jet
75- 76 I2 deg e_Pjet Uncertainty of the position angle of the
15GHz radio jet
78- 95 A18 --- FileName Name of the fits image in subdirectory img
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Acknowledgements:
Sebastien Lambert, sebastien.lambert(at)obspm.fr
(End) Patricia Vannier [CDS] 17-May-2021