Staff View: Interferometric monitoring of gamma-ray bright AGNs: Measuring the magnetic field strength of 4C+29.45?

Interferometric monitoring of gamma-ray bright AGNs: Measuring the magnetic field strength of 4C+29.45?

Aims. We present the results of multi-epoch, multifrequency monitoring of blazar 4C +29.45, which was regularly monitored as part of the Interferometric Monitoring of GAmma-ray Bright Active Galactic Nuclei (iMOGABA) program - a key science program of the Korean Very long baseline interferometry Net...

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Main Authors:	Kang, S., Lee, S. -S., Hodgson, J., Algaba, J. -C., Lee, J. W., Kim, J. -Y., Park, J., Kino, M., Kim, D., Trippe, S.
Format:	Article
Published:	EDP Sciences S A 2021
Subjects:	QB Astronomy
Online Access:	http://eprints.um.edu.my/34358/
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spelling	my.um.eprints.343582022-06-09T06:29:12Z http://eprints.um.edu.my/34358/ Interferometric monitoring of gamma-ray bright AGNs: Measuring the magnetic field strength of 4C+29.45? Kang, S. Lee, S. -S. Hodgson, J. Algaba, J. -C. Lee, J. W. Kim, J. -Y. Park, J. Kino, M. Kim, D. Trippe, S. QB Astronomy Aims. We present the results of multi-epoch, multifrequency monitoring of blazar 4C +29.45, which was regularly monitored as part of the Interferometric Monitoring of GAmma-ray Bright Active Galactic Nuclei (iMOGABA) program - a key science program of the Korean Very long baseline interferometry Network (KVN).Methods. Observations were conducted simultaneously at 22, 43, 86, and 129 GHz over the 4 years from 5 December 2012 to 28 December 2016. We also used additional data from the 15 GHz Owens Valley Radio Observatory (OVRO) monitoring program.Results. From the 15 GHz light curve, we estimated the variability timescales of the source during several radio flux enhancements. We found that the source experienced six radio flux enhancements with variability timescales of 9-187 days during the observing period, yielding corresponding variability Doppler factors of 9-27. From the simultaneous multifrequency KVN observations, we were able to obtain accurate radio spectra of the source and hence to more precisely measure the turnover frequencies nu(r), of synchrotron self-absorption (SSA) emission with a mean value of GHz. Using jet geometry assumptions, we estimated the size of the emitting region at the turnover frequency. We found that the equipartition magnetic field strength is up to two orders of magnitude higher than the SSA magnetic field strength (0.001-0.1 G). This is consistent with the source being particle dominated. We performed a careful analysis of the systematic errors related to the making of these estimations.Conclusions. From the results, we concluded that the equipartition region is located upstream from the SSA region. EDP Sciences S A 2021-07-16 Article PeerReviewed Kang, S. and Lee, S. -S. and Hodgson, J. and Algaba, J. -C. and Lee, J. W. and Kim, J. -Y. and Park, J. and Kino, M. and Kim, D. and Trippe, S. (2021) Interferometric monitoring of gamma-ray bright AGNs: Measuring the magnetic field strength of 4C+29.45? Astronomy & Astrophysics, 651. ISSN 0004-6361, DOI https://doi.org/10.1051/0004-6361/202040198 <https://doi.org/10.1051/0004-6361/202040198>. 10.1051/0004-6361/202040198
institution	Universiti Malaya
building	UM Library
collection	Institutional Repository
continent	Asia
country	Malaysia
content_provider	Universiti Malaya
content_source	UM Research Repository
url_provider	http://eprints.um.edu.my/
topic	QB Astronomy
spellingShingle	QB Astronomy Kang, S. Lee, S. -S. Hodgson, J. Algaba, J. -C. Lee, J. W. Kim, J. -Y. Park, J. Kino, M. Kim, D. Trippe, S. Interferometric monitoring of gamma-ray bright AGNs: Measuring the magnetic field strength of 4C+29.45?
description	Aims. We present the results of multi-epoch, multifrequency monitoring of blazar 4C +29.45, which was regularly monitored as part of the Interferometric Monitoring of GAmma-ray Bright Active Galactic Nuclei (iMOGABA) program - a key science program of the Korean Very long baseline interferometry Network (KVN).Methods. Observations were conducted simultaneously at 22, 43, 86, and 129 GHz over the 4 years from 5 December 2012 to 28 December 2016. We also used additional data from the 15 GHz Owens Valley Radio Observatory (OVRO) monitoring program.Results. From the 15 GHz light curve, we estimated the variability timescales of the source during several radio flux enhancements. We found that the source experienced six radio flux enhancements with variability timescales of 9-187 days during the observing period, yielding corresponding variability Doppler factors of 9-27. From the simultaneous multifrequency KVN observations, we were able to obtain accurate radio spectra of the source and hence to more precisely measure the turnover frequencies nu(r), of synchrotron self-absorption (SSA) emission with a mean value of GHz. Using jet geometry assumptions, we estimated the size of the emitting region at the turnover frequency. We found that the equipartition magnetic field strength is up to two orders of magnitude higher than the SSA magnetic field strength (0.001-0.1 G). This is consistent with the source being particle dominated. We performed a careful analysis of the systematic errors related to the making of these estimations.Conclusions. From the results, we concluded that the equipartition region is located upstream from the SSA region.
format	Article
author	Kang, S. Lee, S. -S. Hodgson, J. Algaba, J. -C. Lee, J. W. Kim, J. -Y. Park, J. Kino, M. Kim, D. Trippe, S.
author_facet	Kang, S. Lee, S. -S. Hodgson, J. Algaba, J. -C. Lee, J. W. Kim, J. -Y. Park, J. Kino, M. Kim, D. Trippe, S.
author_sort	Kang, S.
title	Interferometric monitoring of gamma-ray bright AGNs: Measuring the magnetic field strength of 4C+29.45?
title_short	Interferometric monitoring of gamma-ray bright AGNs: Measuring the magnetic field strength of 4C+29.45?
title_full	Interferometric monitoring of gamma-ray bright AGNs: Measuring the magnetic field strength of 4C+29.45?
title_fullStr	Interferometric monitoring of gamma-ray bright AGNs: Measuring the magnetic field strength of 4C+29.45?
title_full_unstemmed	Interferometric monitoring of gamma-ray bright AGNs: Measuring the magnetic field strength of 4C+29.45?
title_sort	interferometric monitoring of gamma-ray bright agns: measuring the magnetic field strength of 4c+29.45?
publisher	EDP Sciences S A
publishDate	2021
url	http://eprints.um.edu.my/34358/
_version_	1735570302750949376
score	13.211869

Interferometric monitoring of gamma-ray bright AGNs: Measuring the magnetic field strength of 4C+29.45?

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