The Bulletin of The Korean Astronomical Society (천문학회보)
- Volume 46 Issue 1
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- Pages.52.1-52.1
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- 2021
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- 1226-2692(pISSN)
Interferometric Monitoring of Gamma-ray Bright AGNs:Measuring the Magnetic Field Strength of 4C+29.45
- Kang, Sincheol (Korea Astronomy and Space Science institute) ;
- Lee, Sang-Sung (Korea Astronomy and Space Science institute) ;
- Hodgson, Jeffrey (Korea Astronomy and Space Science institute) ;
- Algaba, Juan-Carlos (Department of Physics, Faculty of Science, University of Malaya) ;
- Lee, Jee Won (Korea Astronomy and Space Science institute) ;
- Kim, Jae-Young (Max-Plank-Institut fur Radioastronomie) ;
- Park, Jongho (Institute of Astronomy and Astrophysics, Academia Sinica) ;
- Kino, Motoki (National Astronomical Observatory of Japan) ;
- Kim, Daewon (Department of Physics and Astronomy, Seoul National University) ;
- Trippe, Sascha (Department of Physics and Astronomy, Seoul National University)
- Published : 2021.04.13
Abstract
We present the results of multi-epoch, multi-frequency monitoring of a blazar 4C +29.45, which was regularly monitored as part of the Interferometric Monitoring of GAmma-ray Bright AGNs program - a key science program of the Korean Very long baseline interferometry Network (KVN). Observations were conducted simultaneously at 22, 43, 86 and 129 GHz during the 4 years from December 2012 to December 2016. We also used additional data from the 15 GHz Owens Valley Radio Observatory (OVRO) monitoring program. From the 15 GHz light curve, we estimated the variability time scales of the source during several radio flux enhancements. We found that the source experiencesd 6 radio flux enhancements with variability time scales of 9-187 days during the observing period, yielding corresponding variability Doppler factors of 9-27. From the multi-frequency simultaneous KVN observations, we were able to obtain accurate radio spectra of the source and hence to more precisely measure the turnover frequencies 𝜈r of synchrotron self-absorbed (SSA) emission with a mean value of
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