Compact Bright Radio-loud AGNs. III. A Large VLBA Survey at 43 GHz
Artikel i vetenskaplig tidskrift, 2020

We present the results from the 43 GHz Very Long Baseline Array (VLBA) observations of 124 compact radio-loud active galactic nuclei (AGNs) that were conducted between 2014 November and 2016 May. The typical dimensions of the restoring beam in each image are about 0.5 mas x 0.2 mas. The highest resolution of 0.2 mas corresponds to a physical size of 0.02 pc for the lowest redshift source in the sample. The 43 GHz very long baseline interferometry (VLBI) images of 97 AGNs are presented for the first time. We study the source compactness on milliarcsecond and submilliarcsecond scales, and suggest that 95 sources in our sample are suitable for future space VLBI observations. By analyzing our data supplemented with other VLBA AGN surveys from the literature, we find that the core brightness temperature increases with increasing frequency below a break frequency similar to 7 GHz, and decreases between similar to 7 and 240 GHz but increases again above 240 GHz in the rest frame of the sources. This indicates that the synchrotron opacity changes from optically thick to thin. We also find a strong statistical correlation between radio and gamma-ray flux densities. Our correlation is tighter than those in the literature derived from lower-frequency VLBI data, suggesting that the gamma-ray emission is produced more cospatially with the 43 GHz VLBA core emission. This correlation can also be extrapolated to the unbeamed AGN population, implying that a universal gamma-ray production mechanism might be at work for all types of AGNs.

Active galaxies

Radio loud quasars

Very long baseline interferometry




X-P Cheng

Korea Astronomy and Space Science Institute

Chinese Academy of Sciences

T. An

Chinese Academy of Sciences

S. Frey

Magyar Tudomanyos Akademia

Eötvös Loránd University (ELTE)

X-Y Hong

Chinese Academy of Sciences

X. He

Chinese Academy of Sciences


National Radio Astronomy Observatory

M. L. Lister

Purdue University

B-Q Lao

Chinese Academy of Sciences

X-F Li

Chinese Academy of Sciences

P. Mohan

Chinese Academy of Sciences

Jun Yang

Chinese Academy of Sciences

Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium

X-C Wu

Chinese Academy of Sciences

Z-L Zhang

Chinese Academy of Sciences

Y-K Zhang

Chinese Academy of Sciences

W. Zhao

Chinese Academy of Sciences

Astrophysical Journal, Supplement Series

0067-0049 (ISSN) 1538-4365 (eISSN)

Vol. 247 2 57


Astronomi, astrofysik och kosmologi



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