VLBI observations of a sample of Palomar-Green quasars - I. Parsec-scale morphology
Journal article, 2023

We observed 20 Palomar-Green quasars at low redshi ft (z < 0.5) with total flux density >1 mJy, including four radio-loud quasars (RLQs) and 16 radio-quiet quasars (RQQs), using the Very Long Baseline Array (VLBA) at 5 GHz. 10 RQQs are clearly detected in the VLBA images, and a compact radio core is identified in eight of them, indicating the prevalence of active galactic nucleus (AGN)-related radio emission in this flux-density-limited RQQ sample. The RQQs and RLQs in our sample have a division at similar to 30 mJy. The radio emission from RQQs appears to be the result of a combination of star formation and AGN-associated activities. All RQQs in our sample have a 5 GHz flux density ratio of Very Large Array (VLA) A-array to D-array f(c) = S-A(VLA)/S-D(VLA) above 0.2. The RQQs with f(a)(VLBA and VLA flux density ratio S-VLBA/S-A(VLA)) > 0.2 versus f(a) < 0.2 show significant differences in morphology, compactness, and total flux density. f(a) of RQQs is systematically lower than that of RLQs, probably due to the extended jets or relic jets of RQQs on tens to hundreds parsecs that are resolved out in VLBA images. Future larger samples, especially with the addition of milliarcsec resolution radio images of RQQs with total flux densities below 1 mJy, can test the conclusions of this paper and contribute to the understanding of the radio emission mechanism of RQQs, and the dichotomy and physical connection between RQQs and RLQs.

galaxies: jets

instrumentation: high angular resolution

methods: observational

galaxies: nuclei

Author

Ailing Wang

Chinese Academy of Sciences

Tao An

Chinese Academy of Sciences

Xiaopeng Cheng

Korea Astronomy and Space Science Institute

Luis C. Ho

Beijing University of Technology

Kellermann

National Radio Astronomy Observatory

Willem A. Baan

Netherlands Institute for Radio Astronomy (ASTRON)

Chinese Academy of Sciences

Jun Yang

Chalmers, Space, Earth and Environment, Onsala Space Observatory

Yingkang Zhang

Chinese Academy of Sciences

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 518 1 39-53

Subject Categories

Astronomy, Astrophysics and Cosmology

Environmental Sciences

Medical Image Processing

DOI

10.1093/mnras/stac3091

More information

Latest update

7/5/2023 1