Astrometric Apparent Motion of High-redshift Radio Sources

Abstract

Radio-loud quasars at high redshift (z > 4) are rare objects in the Universe and rarely observed with Very Long Baseline Interferometry (VLBI). But some of them have flux density sufficiently high for monitoring of their apparent position. The instability of the astrometric positions could be linked to the astrophysical process in the jetted active galactic nuclei in the early Universe. Regular observations of the high-redshift quasars are used for estimating their apparent proper motion over several years. We have undertaken regular VLBI observations of several high-redshift quasars at 2.3 GHz (S band) and 8.4 GHz (X band) with a network of five radio telescopes: 40-m Yebes (Spain), 25-m Sheshan (China), and three 32-m telescopes of the Quasar VLBI Network (Russia) -- Svetloe, Zelenchukskaya, and Badary. Additional facilities joined this network occasionally. The sources have also been observed in three sessions with the European VLBI Network (EVN) in 2018--2019 and one Long Baseline Array (LBA) experiment in 2018. In addition, several experiments conducted with the Very Long Baseline Array (VLBA) in 2017--2018were used to improve the time sampling and the statistics. Based on these 37 astrometric VLBI experiments between 2017 and 2021, we estimated the apparent proper motions of four quasars: 0901+697, 1428+422, 1508+572, and 2101+600.

References in corpus (37)

• The Sloan Digital Sky Survey: Technical Summary
• Blazars in the Fermi Era: The OVRO 40-m Telescope Monitoring Program
• DiFX2: A more flexible, efficient, robust and powerful software correlator
• Astrometry and geodesy with radio interferometry: experiments, models, results
• The VLBA Calibrator Survey - VCS1
• The third realization of the International Celestial Reference Frame by very long baseline interferometry
• The Quest for Dual and Binary Supermassive Black Holes: A Multi-Messenger View
• The VLBA Imaging and Polarimetry Survey at 5 GHz
• The Third VLBA Calibrator Survey
• The Sixth VLBA Calibrator Survey: VCS6
• The SFXC software correlator for Very Long Baseline Interferometry: Algorithms and Implementation
• Single-epoch VLBI imaging study of bright active galactic nuclei at 2 and 8 GHz
• Gamma-Ray and Parsec-Scale Jet Properties of a Complete Sample of Blazars From the MOJAVE Program
• Analysis of astrometric catalogues with vector spherical harmonics
• The VLBA Galactic Plane Survey -- VGaPS
• VLBI measurement of the secular aberration drift
• Quasar Proper Motions and Low-Frequency Gravitational Waves
• Q0906+6930: The Highest-Redshift Blazar
• Gravitational Radiation and Very Long Baseline Interferometry
• Dynamics of warped accretion discs
• Blazar Counterparts for 3EG Sources at -40 < decl. < 0: Pushing South Through the Bulge
• Evolving parsec-scale radio structure in the most distant blazar known
• GB1508+5714: a radio-loud quasar with z=4.30 and the space density of high redshift, radio--loud quasars.
• On the connection of the apparent proper motion and the VLBI structure of compact radio sources
• Effect of asymmetry of the radio source distribution on the apparent proper motion kinematic analysis
• J0906+6930: a radio-loud quasar in the early Universe
• A new version of the OCARS catalog of Optical Characteristics of Astrometric Radio Sources
• Physical parameters of a relativistic jet at very high redshift: the case of the blazar J1430+4204
• Radio-loud Quasars above Redshift 4: VLBI Imaging of an Extended Sample
• Fast jet proper motion discovered in a blazar at z = 4.72
• Radio spectra of bright compact sources at z>4.5
• Multi-frequency polarization properties of ten quasars on deca-parsec scales at z > 3
• High-resolution radio imaging of two luminous quasars beyond redshift 4.5
• Testing the Cosmological Principle: Astrometric Limits on Systemic Motion of Quasars at Different Cosmological Epochs
• Optical Spectra of Candidate International Celestial Reference Frame (ICRF) Flat-Spectrum Radio Sources. III
• J2102+6015: a young radio source at z = 4.575
• The Highly Self-Absorbed Blazar, PKS\,1351$-$018

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• Metrics of Astrometric Variability in the International Celestial Reference Frame: I. Statistical analysis and selection of the most variable sources
• Very-long-baseline interferometry study of the flaring blazar TXS 1508+572 in the early Universe
• Milliarcsecond astrometric oscillations in active galactic nuclei as a precursor of multi-messenger gravitational wave events
• J2102+6015: an Intriguing Radio-loud Active Galactic Nucleus in the Early Universe