http://arxiv.org/abs/2110.02973
The first similarities between peaked sources (PS) and narrow-line Seyfert 1 (NLS1) galaxies were noticed already twenty years ago. Nowadays, it is known that several sources can share both classifications, and that part of the parent population of $\gamma$-ray emitting NLS1s could be hiding among PS. In this brief review, we describe how and why this orientation-based unification was developed. We also show how the recent discovery of absorbed radio jets in NLS1s, basically invisible at frequencies below 10 GHz, could impact our knowledge of PS and, in particular, render the widely used radio-loudness parameter obsolete.
M. Berton and E. Järvelä
Fri, 8 Oct 21
24/70
Comments: 4 pages, accepted for publication on Astronomische Nachrichten, Special Issue “6th Workshop on Compact Steep-Spectrum and GHz-peaked spectrum radio sources”
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