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Galaxies
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Jet Physics of Accreting Super Massive Black Holes
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Jet Physics of Accreting Super Massive Black Holes

A special issue of Galaxies (ISSN 2075-4434).

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 26307

Special Issue Editor

Dr. Filippo D'Ammando

E-Mail Website
Guest Editor
INAF-IRA Bologna, 40129 Bologna, BO, Italy
Interests: gamma-ray astronomy; X-ray astronomy; multi-messenger astronomy; accretion and jet physics; emission mechanisms in AGN; multiwavelength studies of radio-loud AGN

Special Issue Information

Dear Colleagues,

Relativistic jets are one of the most powerful manifestations of the release of energy related to the super-massive black hole (SMBH) at the center of active galactic nuclei. Despite decades of efforts, our understanding of several physical aspects of relativistic jets remains elusive: Jet formation, evolution and propagation, its composition and structure, what is the nature of the coupling between the accretion disc and the jet, which are the mechanisms of particles acceleration, the role of the magnetic fields, and where is the location of the high energy emitting region, are among the outstanding open questions in the international astrophysical community.

The observational evidence gathered by the current facilities across the electromagnetic spectrum accompanied by improvements in the theoretical and numerical fields, is offering an unprecedented framework for deriving important clues on the debated problems in jet physics of SMBH.

Galaxies is hosting a Special Issue on Jet Physics of Accreting SMBH. The aim of this Special Issue is to bring together observational astronomers working across the electromagnetic spectrum with theorists in order to investigate our understanding of the jet physics in SMBH.

With this Special Issue, we invite researchers to submit review papers in which the current status of observational, theoretical and numerical studies applied to relativistic jets in AGN is discussed. It will serve also as a common basis for future studies and prospects for observations with next-generation instruments.

Sincerely
Dr. Filippo D'Ammando
Guest Editor

Manuscript Submission Information

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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. Galaxies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). 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
  • relativistic jets
  • multiwavelength observations
  • theoretical emission models
  • relativistic magnetohydrodynamics simulations
  • polarization
  • jet formation
  • magnetic fields

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Published Papers (6 papers)

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Research

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13 pages, 756 KiB  
Article
Metal Content in Relativistically Jetted and Radio-Quiet Quasars in the Main Sequence Context
by Paola Marziani, Swayamtrupta Panda, Alice Deconto Machado and Ascension Del Olmo
Galaxies 2023, 11(2), 52; https://doi.org/10.3390/galaxies11020052 - 30 Mar 2023
Cited by 8 | Viewed by 1596
Abstract
The optical and UV properties of radio-quiet (RQ) and radio-loud (RL, relativistically “jetted”) active galactic nuclei (AGN) are known to differ markedly; however, it is still unclear what is due to a sample selection and what is associated with intrinsic differences in the [...] Read more.
The optical and UV properties of radio-quiet (RQ) and radio-loud (RL, relativistically “jetted”) active galactic nuclei (AGN) are known to differ markedly; however, it is still unclear what is due to a sample selection and what is associated with intrinsic differences in the inner workings of their emitting regions. Chemical composition is an important parameter related to the trends of the quasar main sequence. Recent works suggest that in addition to physical properties such as density, column density, and ionization level, strong Feii emitters require very high metal content. Little is known, however, about the chemical composition of jetted radio-loud sources. In this short note, we present a pilot analysis of the chemical composition of low-z radio-loud and radio-quiet quasars. Optical and UV spectra from ground and space were combined to allow for precise measurements of metallicity-sensitive diagnostic ratios. The comparison between radio-quiet and radio-loud was carried out for sources in the same domain of the Eigenvector 1/main sequence parameter space. Arrays of dedicated photo-ionization simulations with the input of appropriate spectral energy distributions indicate that metallicity is sub-solar for RL AGN, and slightly sub-solar or around solar for RQ AGN. The metal content of the broad line-emitting region likely reflects a similar enrichment story for both classes of AGN not involving recent circum-nuclear or nuclear starbursts. Full article
(This article belongs to the Special Issue Jet Physics of Accreting Super Massive Black Holes)
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12 pages, 813 KiB  
Article
Optical Characteristics of Electromagnetic Radiation, Emitted by Particles or Stars Moving near Supermassive Black Hole
by Stanislav Komarov
Galaxies 2021, 9(3), 57; https://doi.org/10.3390/galaxies9030057 - 18 Aug 2021
Viewed by 1752
Abstract
The general problem of calculating of the propagation of electromagnetic radiation from particles or stars moving in the vicinity of a supermassive black hole is considered in geometrical optics approximation within the framework of the general theory of relativity. Different approaches that can [...] Read more.
The general problem of calculating of the propagation of electromagnetic radiation from particles or stars moving in the vicinity of a supermassive black hole is considered in geometrical optics approximation within the framework of the general theory of relativity. Different approaches that can be used to calculate certain characteristics of radiation, including redshift, the intensity and rotation of the plane of polarization, which have been presented in the literature are analysed herein. The inverse problem—the calculation of the parameters of the motion of the source (star or particle) from the data of the redshift, the intensity and the plane of polarization—is also considered. Full article
(This article belongs to the Special Issue Jet Physics of Accreting Super Massive Black Holes)
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Review

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10 pages, 534 KiB  
Review
Big and Young Supermassive Black Holes in the Early Universe
by Tullia Sbarrato
Galaxies 2021, 9(2), 23; https://doi.org/10.3390/galaxies9020023 - 30 Mar 2021
Cited by 12 | Viewed by 2613
Abstract
Blazars are active galactic nuclei characterized by relativistic jets launched in the vicinity of the central engine (i.e., a supermassive black hole), which are oriented close to our line of sight. Their peculiar orientation makes them very efficient tracers of the overall jetted [...] Read more.
Blazars are active galactic nuclei characterized by relativistic jets launched in the vicinity of the central engine (i.e., a supermassive black hole), which are oriented close to our line of sight. Their peculiar orientation makes them very efficient tracers of the overall jetted population, and due to their brightness they can be visible up to very high redshifts. A deep knowledge of these objects can provide fundamental clues to the models of formation and growth of the first supermassive black holes, but the search for them in the early Universe must be careful and follow a systematic approach. The discovery in the last ∼15 years of extremely massive blazars at very high redshifts (MBH>109M⊙, z>4) revolutionized our perception of their earliest evolution: there seem to be different formation epochs for extremely massive black holes hosted in jetted (z∼4) and non-jetted (z∼2.5) systems. This is not easy to explain, since one would expect jetted sources to accrete less efficiently. Small differences in the population are also derived from the search for such high-z sources. We will go through the open questions in order to understand where the common knowledge stands and which steps must be taken to better understand the formation and common evolution of supermassive black holes and jets in the early Universe. Full article
(This article belongs to the Special Issue Jet Physics of Accreting Super Massive Black Holes)
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32 pages, 1107 KiB  
Review
Leptonic and Hadronic Radiative Processes in Supermassive-Black-Hole Jets
by Matteo Cerruti
Galaxies 2020, 8(4), 72; https://doi.org/10.3390/galaxies8040072 - 1 Oct 2020
Cited by 47 | Viewed by 6002
Abstract
Supermassive black holes lying in the center of galaxies can launch relativistic jets of plasma along their polar axis. The physics of black-hole jets is a very active research topic in astrophysics, owing to the fact that many questions remain open on the [...] Read more.
Supermassive black holes lying in the center of galaxies can launch relativistic jets of plasma along their polar axis. The physics of black-hole jets is a very active research topic in astrophysics, owing to the fact that many questions remain open on the physical mechanisms of jet launching, of particle acceleration in the jet, and on the radiative processes. In this work I focus on the last item, and present a review of the current understanding of radiative emission processes in supermassive-black-hole jets. Full article
(This article belongs to the Special Issue Jet Physics of Accreting Super Massive Black Holes)
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28 pages, 3043 KiB  
Review
Relativistic Jets from AGN Viewed at Highest Angular Resolution
by Kazuhiro Hada
Galaxies 2020, 8(1), 1; https://doi.org/10.3390/galaxies8010001 - 18 Dec 2019
Cited by 20 | Viewed by 8873
Abstract
Accreting supermassive black holes in active galactic nuclei (AGN) produce powerful relativistic jets that shine from radio to GeV/TeV γ-rays. Over the past decade, AGN jets have extensively been studied in various energy bands and our knowledge about the broadband emission and rapid [...] Read more.
Accreting supermassive black holes in active galactic nuclei (AGN) produce powerful relativistic jets that shine from radio to GeV/TeV γ-rays. Over the past decade, AGN jets have extensively been studied in various energy bands and our knowledge about the broadband emission and rapid flares are now significantly updated. Meanwhile, the progress of magnetohydrodynamic simulations with a rotating black hole have greatly improved our theoretical understanding of powerful jet production. Nevertheless, it is still challenging to observationally resolve such flaring sites or jet formation regions since the relevant spatial scales are tiny. Observations with very long baseline interferometry (VLBI) are currently the only way to directly access such compact scales. Here we overview some recent progress of VLBI studies of AGN jets. As represented by the successful black hole shadow imaging with the Event Horizon Telescope, the recent rapid expansion of VLBI capability is remarkable. The last decade has also seen a variety of advances thanks to the advent of RadioAstron, GMVA, new VLBI facilities in East Asia as well as to the continued upgrade of VLBA. These instruments have resolved the innermost regions of relativistic jets for a number of objects covering a variety of jetted AGN classes (radio galaxies, blazars, and narrow-line Seyfert 1 galaxies), and the accumulated results start to establish some concrete (and likely universal) picture on the collimation, acceleration, recollimation shocks, magnetic field topology, and the connection to high-energy flares in the innermost part of AGN jets. Full article
(This article belongs to the Special Issue Jet Physics of Accreting Super Massive Black Holes)
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19 pages, 5355 KiB  
Review
Blazar Optical Polarimetry: Current Progress in Observations and Theories
by Haocheng Zhang
Galaxies 2019, 7(4), 85; https://doi.org/10.3390/galaxies7040085 - 27 Oct 2019
Cited by 21 | Viewed by 4206
Abstract
Polarimetry has been a standard tool to probe the active galactic nucleus (AGN) jet magnetic field. In recent years, several optical polarization monitoring programs have been carried out, bringing in many exciting new results and insights into jet dynamics and emission. This article [...] Read more.
Polarimetry has been a standard tool to probe the active galactic nucleus (AGN) jet magnetic field. In recent years, several optical polarization monitoring programs have been carried out, bringing in many exciting new results and insights into jet dynamics and emission. This article discusses current progress in blazar optical polarimetry. The main focus is the variability of polarization signatures, which has spurred a lot of theoretical studies. These novel developments have provided unique constraints on the blazar flares and emphasized the role of the magnetic field in jet evolution. Optical polarimetry will continue to act as an essential component in the multi-messenger study of AGN jets, in particular with the upcoming high-energy polarimetry. Comparing to first-principle numerical simulations, future multi-wavelength polarimetry can shed light on jet dynamics, particle acceleration, and radiation processes. Full article
(This article belongs to the Special Issue Jet Physics of Accreting Super Massive Black Holes)
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