Relativistic Jets in Active Galactic Nuclei

2014 ◽  
Author(s):  
Geoffrey Bicknell ◽  
Mohammad Nawaz ◽  
Alexander Wagner ◽  
Masayuki Umemura ◽  
Brian McNamara ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Relativistic Jets

scholarly journals Polarimetric Properties of Blazars Caught by the WEBT

Galaxies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 42
Author(s):  
Claudia M. Raiteri ◽  
Massimo Villata
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Plasma Jets ◽  
Line Of Sight ◽  
Optical Behaviour ◽  
Relativistic Jets ◽  
Comprehensive Picture ◽  
Multi Wavelength ◽  
Extreme Variability ◽  
Continuous Range

Active galactic nuclei come in many varieties. A minority of them are radio-loud, and exhibit two opposite prominent plasma jets extending from the proximity of the supermassive black hole up to megaparsec distances. When one of the relativistic jets is oriented closely to the line of sight, its emission is Doppler beamed and these objects show extreme variability properties at all wavelengths. These are called “blazars”. The unpredictable blazar variability, occurring on a continuous range of time-scales, from minutes to years, is most effectively investigated in a multi-wavelength context. Ground-based and space observations together contribute to give us a comprehensive picture of the blazar emission properties from the radio to the γ-ray band. Moreover, in recent years, a lot of effort has been devoted to the observation and analysis of the blazar polarimetric radio and optical behaviour, showing strong variability of both the polarisation degree and angle. The Whole Earth Blazar Telescope (WEBT) Collaboration, involving many tens of astronomers all around the globe, has been monitoring several blazars since 1997. The results of the corresponding data analysis have contributed to the understanding of the blazar phenomenon, particularly stressing the viability of a geometrical interpretation of the blazar variability. We review here the most significant polarimetric results achieved in the WEBT studies.

The GLEAM 4-Jy Sample: The brightest radio-sources in the southern sky

2019 ◽  
Vol 15 (S356) ◽  
pp. 375-375
Author(s):  
Sarah White
Keyword(s):  
Radio Emission ◽  
Active Galactic Nuclei ◽  
Visual Inspection ◽  
Low Frequency ◽  
Galactic Nuclei ◽  
Radio Sources ◽  
Relativistic Jets ◽  
The Galaxy ◽  
Murchison Widefield Array ◽  
Past Activity

AbstractLow-frequency radio emission allows powerful active galactic nuclei (AGN) to be selected in a way that is unaffected by dust obscuration and orientation of the jet axis. It also reveals past activity (e.g. radio lobes) that may not be evident at higher frequencies. Currently, there are too few “radio-loud” galaxies for robust studies in terms of redshift-evolution and/or environment. Hence our use of new observations from the Murchison Widefield Array (the SKA-Low precursor), over the southern sky, to construct the GLEAM 4-Jy Sample (1,860 sources at S151MHz > 4 Jy). This sample is dominated by AGN and is 10 times larger than the heavily relied-upon 3CRR sample (173 sources at S178MHz > 10 Jy) of the northern hemisphere. In order to understand how AGN influence their surroundings and the way galaxies evolve, we first need to correctly identify the galaxy hosting the radio emission. This has now been completed for the GLEAM 4-Jy Sample – through repeated visual inspection and extensive checks against the literature – forming a valuable, legacy dataset for investigating relativistic jets and their interplay with the environment.

scholarly journals Intrinsic physical conditions and structure of relativistic jets in active galactic nuclei

2015 ◽  
Vol 447 (3) ◽  
pp. 2726-2737 ◽  
Author(s):  
E. E. Nokhrina ◽  
V. S. Beskin ◽  
Y. Y. Kovalev ◽  
A. A. Zheltoukhov
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Relativistic Jets ◽  
Physical Conditions

scholarly journals High Resolution X-ray Spectroscopy of Active Galactic Nuclei

1990 ◽  
Vol 115 ◽  
pp. 262-273
Author(s):  
Julian H. Krolik
Keyword(s):  
High Resolution ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Light Sources ◽  
Clusters Of Galaxies ◽  
Relativistic Jets ◽  
Bl Lac Objects ◽  
X Ray ◽  
Interstellar Material ◽  
Scientific Value

AbstractHigh-resolution X-ray spectroscopy has the potential to reveal a number of interesting features of active galactic nuclei, primarily, though not exclusively, through the measurement of absorption lines. After a brief review of the principal problems of AGN research, selected potential high-resolution observations are discussed with a view toward assessing their scientific value and the degree of resolution they will require. Two classes of observations pertaining directly to AGNs are discussed: Fe Kα spectroscopy relevant to the dynamical and thermal character of the emission line zones; and measurement of resonance line absorption by highly-ionized species in BL Lac objects, which should tell us about entrainment of interstellar material by relativistic jets. A third class of potentially important observations uses AGNs as background light sources in order to directly measure the distance to clusters of galaxies.

scholarly journals On the radio image of relativistic jets – I. Internal structure, Doppler boosting, and polarization maps

2019 ◽  
Vol 488 (1) ◽  
pp. 224-233 ◽  
Author(s):  
A V Chernoglazov ◽  
V S Beskin ◽  
V I Pariev
Keyword(s):  
Active Galactic Nuclei ◽  
Internal Structure ◽  
Linear Polarization ◽  
Ambient Pressure ◽  
Galactic Nuclei ◽  
Synchrotron Emission ◽  
Relativistic Jets ◽  
Radio Image ◽  
Radial Profiles

ABSTRACT In this first paper from forthcoming series of works devoted to radio image of relativistic jets from active galactic nuclei the role of internal structure of a flow is discussed. We determine the radial profiles of all physical values for reasonable Michel magnetization parameter σM and ambient pressure Pext. Maps of Doppler boosting factor δ and observed directions of linear polarization of synchrotron emission are also constructed.

scholarly journals Observational View of Magnetic Fields in Active Galactic Nuclei Jets

2016 ◽  
Vol 12 (S324) ◽  
pp. 149-156
Author(s):  
Talvikki Hovatta
Keyword(s):  
Black Hole ◽  
Magnetic Fields ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Short Review ◽  
Relativistic Jets ◽  
The Past ◽  
Emission Models ◽  
Active Galactic Nuclei Jets ◽  
The Magnetic Field

AbstractAccording to the currently favored picture, relativistic jets in active galactic nuclei (AGN) are launched in the vicinity of the black hole by magnetic fields extracting energy from the spinning black hole or the accretion disk. In the past decades, various models from shocks to magnetic reconnection have been proposed as the energy dissipation mechanism in the jets. This paper presents a short review on how linear polarization observations can be used to constrain the magnetic field structure in the jets of AGN, and how the observations can be used to constrain the various emission models.

scholarly journals Multi-wavelength observations of the narrow-line Seyfert 1 galaxy RX J2314.9+2243

2014 ◽  
Vol 10 (S312) ◽  
pp. 61-62
Author(s):  
S. Komossa ◽  
I. Myserlis ◽  
L. Fuhrmann ◽  
D. Xu ◽  
D. Grupe ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Extreme Case ◽  
Narrow Line ◽  
Relativistic Jets ◽  
Uv Spectrum ◽  
New Radio ◽  
Multi Wavelength ◽  
Low Mass ◽  
Black Hole Masses

AbstractNarrow-line Seyfert 1 (NLS1) galaxies are a sub-class of active galactic nuclei (AGN) with relatively low-mass black holes, accreting near the Eddington rate. A small fraction of them is radio-loud and harbors relativistic jets. As a class, these provide us with new insights into the cause(s) of radio-loudness, the blazar phenomenon at low black hole masses, and the operation of radio-mode feedback. The NLS1 galaxy RXJ2314.9+2243 is remarkable for its multi-wavelength properties. We present new radio observations taken at Effelsberg, and a summary of the recent results from our multi-wavelength study. RXJ2314.9+2243 is radio-loud, luminous in the infrared, has a flat X-ray spectrum and peculiar UV spectrum, and hosts an exceptionally broad and blueshifted [OIII]λ5007 emission line, indicating the presence of a strong outflow. RXJ2314.9+2243 likely represents an extreme case of AGN induced feedback in the local universe.

scholarly journals Some Notes About the Current Researches on the Physics of Relativistic Jets

2022 ◽  
Vol 8 ◽  
Author(s):  
Luigi Foschini
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Specific Reference ◽  
Relativistic Jets

Some highlights of the recent researches in the field of relativistic jets are reviewed and critically analyzed. Given the extent of the available literature, this essay symbolically takes the baton from the outstanding and recent review by Blandford, Meier, and Readhead (2019). Therefore, I focus mostly on the results published during the latest few years, with specific reference to jets from active galactic nuclei.

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