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Universe
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Seyfert Galaxies Astrophysics
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Seyfert Galaxies Astrophysics

A special issue of Universe (ISSN 2218-1997).

Deadline for manuscript submissions: closed (31 March 2020) | Viewed by 14965

Special Issue Editor

Dr. Luigi Foschini

E-Mail Website
Guest Editor
National Institute of Astrophysics (INAF) – Brera Astronomical Observatory, Merate, Italy
Interests: active galactic nuclei; foundations of physics; high-energy astrophysics; physics of time; quantum gravity; relativistic astrophysics; relativistic jets; X-ray binaries

Special Issue Information

Dear Colleagues,

Carl Seyfert published, in 1943, his seminal paper about a handful of bright galaxies with anomalously wide emission lines. Today, an entire class of active galactic nuclei (AGN) has been named after him. Seyfert galaxies offer the possibility to study the physics of a wide variety of phenomena: accretion onto supermassive black holes, ejection of matter at relativistic speed either collimated (jets) or not (winds), and large-scale processes and feedback with the host galaxy. In the case of low redshift and bright objects, the study could reach a significant level of detail, so that it could serve as a benchmark for comparative studies on any other type of AGN.

The aim of the present Special Issue is to gather different point of views on these topics, in order to build a general and reliable picture of the nature of Seyfert galaxies.

Dr. Luigi Foschini
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Universe is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • active galactic nuclei
  • Seyfert galaxies
  • supermassive black hole
  • accretion physics
  • relativistic jets
  • winds and outflows
  • feedback
  • host galaxy

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Published Papers (6 papers)

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Editorial

Jump to: Research

2 pages, 186 KiB  
Editorial
Seyfert Galaxies Astrophysics
by Luigi Foschini
Universe 2020, 6(8), 126; https://doi.org/10.3390/universe6080126 - 17 Aug 2020
Cited by 1 | Viewed by 1843
Abstract
Looking back in time, it is somehow surprising to see the enormous advancement made by astrophysics in just about one century [...] Full article
(This article belongs to the Special Issue Seyfert Galaxies Astrophysics)

Research

Jump to: Editorial

11 pages, 952 KiB  
Article
Obscuration and Scattering in Narrow-Line Seyfert 1s
by Xiang Pan, Hongyan Zhou and Peng Jiang
Universe 2020, 6(6), 73; https://doi.org/10.3390/universe6060073 - 28 May 2020
Cited by 1 | Viewed by 1815
Abstract
Narrow-line Seyfert 1s (NLS1s) observed at large inclinations from face-on are important for understanding this amazing AGN subclass. However, progress is slowly being made in the huntings and studies of highly obscured (EB–V ≥ 1) NLS1s. Recently, we discovered that multi-wavelength [...] Read more.
Narrow-line Seyfert 1s (NLS1s) observed at large inclinations from face-on are important for understanding this amazing AGN subclass. However, progress is slowly being made in the huntings and studies of highly obscured (EB–V ≥ 1) NLS1s. Recently, we discovered that multi-wavelength photometric and polarimetric analysis can be of great help in identifying and studying highly obscured NLS1s. This paper presents an intercomparison study of three typical highly obscured NLS1s. By joint analysis of extinction, absorption lines, and scattered AGN radiation, properties of the nucleus (disk and broad emission line regions) are measured. Physical and geometrical conditions about circum-nucleus obscuring/scattering clouds are also estimated. In addition, the host galaxies which are usually difficult to observe in such high luminosity NLS1s are also revealed in these targets. The results show that obscuration and scattering can be powerful probes to obscured NLS1s. Analogues of these obscured NLS1s are found to widely exist. In addition, they will be followed up in our future works, so as to understand the nuclei, circum-nucleus clouds, and host galaxies of NLS1s. Full article
(This article belongs to the Special Issue Seyfert Galaxies Astrophysics)
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9 pages, 397 KiB  
Article
The Jet-Disk Coupling of Seyfert Galaxies from a Complete Hard X-ray Sample
by Xiang Liu, Ning Chang, Zhenhua Han and Xin Wang
Universe 2020, 6(5), 68; https://doi.org/10.3390/universe6050068 - 10 May 2020
Cited by 4 | Viewed by 2442
Abstract
We analyze the jet-disk coupling for different subsamples from a complete hard X-ray Seyfert sample to study the coupling indices and their relation to accretion rate. The results are: (1) the power-law coupling index ranges from nearly unity (linear correlation) for radio loud [...] Read more.
We analyze the jet-disk coupling for different subsamples from a complete hard X-ray Seyfert sample to study the coupling indices and their relation to accretion rate. The results are: (1) the power-law coupling index ranges from nearly unity (linear correlation) for radio loud Seyferts to significantly less than unity for radio quiet ones. This decline trend of coupling index also holds from larger sources to compact ones; (2) the Seyferts with intermediate to high accretion rate (Eddington ratio λ ∼ 0.001 to 0.3) show a linear jet-disk coupling, but it shallows from near to super Eddington ( λ ∼ 0.3 to 10), and the former is more radio loud than the latter; (3) the Seyfert 1s are slightly steeper than the Seyfert 2s, in the jet-disk correlation. In the linear coupling regime, the ratio of jet efficiency to radiative efficiency ( η / ε ) is nearly invariant, but in low accretion or super accretion regime, η / ε varies with λ in our model. We note that a radio-active cycle of accretion-dominated active galactic nuclei would be: from a weaker jet-disk coupling in λ < 0 . 001 for low luminosity Seyferts, to a linear coupling in 0 . 001 < λ < 0 . 3 for radio-loud luminous Seyferts and powerful radio galaxies/quasars, and to a weaker coupling in 0 . 3 < λ < 10 ones. Full article
(This article belongs to the Special Issue Seyfert Galaxies Astrophysics)
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10 pages, 917 KiB  
Article
High-Energy and Very High-Energy Constraints from Log-Parabolic Spectral Models in Narrow-Line Seyfert 1 Galaxies
by Stefano Vercellone, Luigi Foschini, Patrizia Romano, Markus Böttcher and Catherine Boisson
Universe 2020, 6(4), 54; https://doi.org/10.3390/universe6040054 - 16 Apr 2020
Cited by 2 | Viewed by 2431
Abstract
Narrow-line Seyfert 1 galaxies (NLSy1s) are a well established class of γ -ray sources, showing the presence of a jet like the more common flat-spectrum radio quasars. The evidence of γ -ray emission poses the issue of the location of the γ -ray [...] Read more.
Narrow-line Seyfert 1 galaxies (NLSy1s) are a well established class of γ -ray sources, showing the presence of a jet like the more common flat-spectrum radio quasars. The evidence of γ -ray emission poses the issue of the location of the γ -ray emitting zone and of the contribution of the γ - γ absorption within the broad-line region (BLR), since such objects have been detected by Fermi-LAT in the MeV-GeV energy range but not by imaging atmospheric Cherenkov telescopes beyond 100 GeV. We discuss how the spectral properties of three NLSy1s (SBS 0846+513, PMN J0948+0022, and PKS 1502+036) derived from the Fermi Large Area Telescope Fourth Source Catalog (4FGL) compared with theoretical models based on the observed properties of the BLR. In particular, we focus on the question on how simple power-law spectral models and log-parabolic ones could be disentangled in γ -ray narrow-line Seyfert 1 galaxies by means of current Fermi-LAT or future imaging atmospheric Cherenkov telescopes data. We found that the only possibility for a log-parabolic model to mimic a power-law model in the energy band above E ∼ 100 GeV is to have a very small value of the curvature parameter β ∼ 0.05 . Full article
(This article belongs to the Special Issue Seyfert Galaxies Astrophysics)
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12 pages, 621 KiB  
Article
Revisiting the Fraction of Radio-Loud Narrow Line Seyfert 1 Galaxies with LoTSS DR1
by Xu-Liang Fan
Universe 2020, 6(3), 45; https://doi.org/10.3390/universe6030045 - 18 Mar 2020
Cited by 3 | Viewed by 2347
Abstract
Radio-Loud narrow-line Seyfert 1 galaxies (NLS1s), especially the extremely radio-loud ones, are widely accepted as the jetted versions of NLS1s. We explore the radio-loud fraction for NLS1s with recently released LoTSS DR1 at 150 MHz. The radio detection rate is about 28% for [...] Read more.
Radio-Loud narrow-line Seyfert 1 galaxies (NLS1s), especially the extremely radio-loud ones, are widely accepted as the jetted versions of NLS1s. We explore the radio-loud fraction for NLS1s with recently released LoTSS DR1 at 150 MHz. The radio detection rate is about 28% for LoTSS DR1. The radio detected NLS1s have lower redshift than the non-detected ones. Moreover, the 150 MHz radio luminosities of NLS1s detected by LoTSS are about two orders of magnitude weaker than those of the previous samples. By defining the radio loudness with the ratio between 150 MHz radio flux and SDSS r band flux, the radio-loud fraction is about 1% with the critical radio loudness equalling 100. Radio loudness shows no dependence on central black hole mass, while weak correlations are found between radio loudness and disk luminosity, as well as Eddington ratio. Full article
(This article belongs to the Special Issue Seyfert Galaxies Astrophysics)
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9 pages, 604 KiB  
Article
Mapping the Narrow-Line Seyfert 1 Galaxy 1H 0323+342
by Luigi Foschini, Stefano Ciroi, Marco Berton, Stefano Vercellone, Patrizia Romano and Valentina Braito
Universe 2019, 5(9), 199; https://doi.org/10.3390/universe5090199 - 14 Sep 2019
Cited by 5 | Viewed by 3186
Abstract
Taking advantage of the most recent measurements by means of high-resolution radio observations and other multiwavelength campaigns, it is possible to elaborate a detailed map of the narrow-line Seyfert 1 Galaxy 1H 0323 + 342 . This map will open the possibility of [...] Read more.
Taking advantage of the most recent measurements by means of high-resolution radio observations and other multiwavelength campaigns, it is possible to elaborate a detailed map of the narrow-line Seyfert 1 Galaxy 1H 0323 + 342 . This map will open the possibility of intriguing hypotheses about the generation of high-energy γ rays in the narrow-line region. Full article
(This article belongs to the Special Issue Seyfert Galaxies Astrophysics)
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