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Review

Jetted Narrow-Line Seyfert 1 Galaxies & Co.: Where Do We Stand?

INAF Brera Astronomical Observatory, 23807 Merate, Italy
Universe 2020, 6(9), 136; https://doi.org/10.3390/universe6090136
Received: 30 July 2020 / Revised: 21 August 2020 / Accepted: 23 August 2020 / Published: 26 August 2020
(This article belongs to the Special Issue Universe: 5th Anniversary)
The discovery in 2008 of high-energy gamma-rays from Narrow-Line Seyfert 1 Galaxies (NLS1s) made it clear that there were active galactic nuclei (AGN) other than blazars and radio galaxies that can eject powerful relativistic jets. In addition to NLS1s, the great performance of the Fermi Large Area Telescope made it possible to discover MeV-GeV photons emitted from more classes of AGN, like Seyferts, Compact Steep Spectrum Gigahertz Peaked Sources (CSS/GPS), and disk-hosted radio galaxies. Although observations indicate a variety of objects, their physical characteristics point to a central engine powered by a relatively small-mass black hole (but, obviously, there are interpretations against this view). This essay critically reviews the literature published on these topics during the last eight years and analyzes the perspectives for the forthcoming years. View Full-Text
Keywords: relativistic jets; active galactic nuclei; Seyfert; blazar; high-energy gamma rays relativistic jets; active galactic nuclei; Seyfert; blazar; high-energy gamma rays
MDPI and ACS Style

Foschini, L. Jetted Narrow-Line Seyfert 1 Galaxies & Co.: Where Do We Stand? Universe 2020, 6, 136. https://doi.org/10.3390/universe6090136

AMA Style

Foschini L. Jetted Narrow-Line Seyfert 1 Galaxies & Co.: Where Do We Stand? Universe. 2020; 6(9):136. https://doi.org/10.3390/universe6090136

Chicago/Turabian Style

Foschini, Luigi. 2020. "Jetted Narrow-Line Seyfert 1 Galaxies & Co.: Where Do We Stand?" Universe 6, no. 9: 136. https://doi.org/10.3390/universe6090136

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