Global millimeter VLBI array survey of ultracompact extragalactic radio sources at 86 GHz
Dhanya G. Nair, Andrei P. Lobanov, Thomas P. Krichbaum, Eduardo Ros, J. Anton Zensus, Yuri Y. Kovalev, Sang-Sung Lee, Florent Mertens, Yoshiaki Hagiwara, Michae… 展开作者
Dhanya G. Nair, Andrei P. Lobanov, Thomas P. Krichbaum, Eduardo Ros, J. Anton Zensus, Yuri Y. Kovalev, Sang-Sung Lee, Florent Mertens, Yoshiaki Hagiwara, Michael Bremer, Michael Lindqvist, Pablo de Vicente
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25 pages, 12 figures, 7 tables, accepted for publication in A&A
(abridged) Very long baseline interferometry (VLBI) observations at 86$\,$GHz (wavelength, $λ= 3\,$mm) reach a resolution of about 50 $μ$as, probing the collimation and acceleration regions of relativistic outflows in active galactic nuclei. To extend the statistical studies of compact extragalactic jets, a large global 86 GHz VLBI survey of 162 radio sources was conducted in 2010-2011 using the Global Millimeter VLBI Array. The survey data attained a typical baseline sensitivity of 0.1 Jy and a typical image sensitivity of 5 mJy/beam, providing successful detections and images for all of the survey targets. For 138 objects, the survey provides the first ever VLBI images made at 86 GHz. Gaussian model fitting of the visibility data was applied to represent the structure of the sources. The Gaussian model-fit-based estimates of brightness temperature ($T_\mathrm{b}$) at the jet base (core) and in moving regions (jet components) downstream from the core were compared to the estimates of $T_\mathrm{b}$ limits made directly from the visibility data, demonstrating a good agreement between the two methods. The apparent brightness temperature estimates for the jet cores in our sample range from $2.5 \times 10^{9}\,$K to $ 1.3\times 10^{12}\,$K. A population model with a single intrinsic value of brightness temperature, $T_\mathrm{0}$, is applied to reproduce the observed $T_\mathrm{b}$ distribution. It yields $T_\mathrm{0} = (3.77^{+0.10}_{-0.14}) \times 10^{11}\,$K for the jet cores, implying that the inverse Compton losses dominate the emission. In the jet components, $T_\mathrm{0} =(1.42^{+0.16}_{-0.19})\times 10^{11}\,$K is found, slightly higher than the equipartition limit of $\sim5\times 10^{10}\,$K expected for these jet regions. For objects with sufficient structural detail detected, the adiabatic energy losses dominate the observed changes of $T_\mathrm{b}$ along the jet.
SKA VLBI survey of the Southern sky for astrometry, geodesy, and astrophysics
GFZ Helmholtz Centre for Geosciences（GFZ亥姆霍兹地学研究中心）；NASA Goddard Space Flight Center（美国国家航空航天局戈达德太空飞行中心）；Max Planck Institute for Radio Astronomy（马克斯·普朗克射电天文研究所）
Molecular absorption lines toward the Galactic ISM detected at 89 GHz with VLBI
Graduate School of Science and Engineering, Kagoshima University（鹿儿岛大学理工学研究科）；Nobeyama Radio Observatory, National Astronomical Observatory of Japan (NAOJ), National Institutes of Natural Sciences (NINS)（日本国立天文台野边山射电天文台，日本国立自然科学研究所）；Amanogawa Galaxy Astronomy Research Center, Graduate School of Science and Engineering, Kagoshima University（鹿儿岛大学理工学研究科银河天文学研究中心）；Center for General Education, Institute for Comprehensive Education, Kagoshima University（鹿儿岛大学综合教育院通识教育中心）；Korea Astronomy and Space Science Institute（韩国天体宇宙科学研究所）
The Celestial Reference Frame at K Band: The CRF-K-2025 Catalog
U.S. Naval Observatory（美国海军天文台）；South African Radio Astronomy Observatory (SARAO)（南非射电天文观测台）；Jet Propulsion Laboratory, California Institute of Technology/NASA（加州理工学院/美国国家航空航天局喷气推进实验室）；TU Wien, Department of Geodesy and Geoinformation（维也纳工业大学大地测量与地理信息系）；German Space Agency within DLR（德国航空航天中心下属德国航天局）；University of Tasmania（塔斯马尼亚大学）；Observatorio Astronómico Nacional, IGN, Spain（西班牙国家地理研究所国家天文台）；Korea Astronomy and Space Science Institute, Korea（韩国天体宇宙科学研究所）；Sejong University, Korea（韩国世宗大学）
SKA-VLBI Probes of High-energy Emission Processes in Relativistic Jets
University of Manchester（曼彻斯特大学）；University of Bristol（布里斯托大学）；Max Planck Institute for Radio Astronomy（马克斯·普朗克射电天文研究所）；Joint Institute for VLBI ERIC（甚长基线干涉测量联合研究所）；University of Turku（图尔库大学）；Aalto University（阿尔托大学）
Absolute kinematics of radio-source components in the complete S5 polar cap sample. IV. Proper motions of the radio cores over a decade and spectral properties
