Absorbed relativistic jets in radio-quiet narrow-line Seyfert 1 galaxies

Narrow-line Seyfert 1 (NLS1) galaxies are peculiar active galactic nuclei. Most of them do not show strong radio emission, but seven radio-quiet (or radio-silent) NLS1s have recently been detected flaring multiple times at 37 GHz by the Metsähovi Radio Telescope, indicating relativistic jets in thes...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 2020-04, Vol.636, p.A64
Main Authors: Berton, M., Järvelä, E., Crepaldi, L., Lähteenmäki, A., Tornikoski, M., Congiu, E., Kharb, P., Terreran, G., Vietri, A.
Format: Article
Language:English
Subjects:
Absorption
Active galactic nuclei
Loudness
Radio emission
Radio observation
Radio telescopes
Relativistic effects
Seyfert galaxies
Synchrotrons
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Summary:Narrow-line Seyfert 1 (NLS1) galaxies are peculiar active galactic nuclei. Most of them do not show strong radio emission, but seven radio-quiet (or radio-silent) NLS1s have recently been detected flaring multiple times at 37 GHz by the Metsähovi Radio Telescope, indicating relativistic jets in these peculiar sources. We observed them with the Karl G. Jansky Very Large Array (JVLA) in A configuration at 1.6, 5.2, and 9.0 GHz. Our results show that these sources are either extremely faint or not detected in the JVLA bands. At these frequencies, the radio emission from their relativistic jet must be absorbed, either through synchrotron self-absorption as it occurs in gigahertz-peaked sources, or more likely, through free-free absorption by a screen of ionized gas associated with starburst activity or shocks. Our findings cast new shadows on the radio-loudness criterion, which seems to be increasingly frequently a misleading parameter. New high-frequency and high-resolution radio observations are essential to test our hypotheses.
ISSN:0004-6361
1432-0746
DOI:10.1051/0004-6361/202037793