Study of the physical conditions in active galactic nuclei. A method for estimating the physical parameters of radio sources

2006 ◽  
Vol 50 (3) ◽  
pp. 194-201 ◽  
Author(s):  
V. S. Artyukh ◽  
P. A. Chernikov
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Physical Parameters ◽  
Radio Sources ◽  
Physical Conditions

scholarly journals The Electron-Positron Cauldron and the Formation of the Hard Radiation of Quasars and AGN

1986 ◽  
Vol 119 ◽  
pp. 383-393
Author(s):  
N.S. Kardashev ◽  
I.D. Novikov ◽  
B.E. Stern
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Physical Parameters ◽  
Physical Processes ◽  
Physical Conditions ◽  
Electron Positron ◽  
Hard Radiation ◽  
The Universe

Active Galactic Nuclei (AGN) and quasars have unique physical parameters among all the objects in the Universe. Undoubtedly it is the uniqueness of the physical conditions in these systems that gives rise to the peculiar physical processes in them.

scholarly journals ROSAT Studies of Extragalactic Radio Sources

1996 ◽  
Vol 175 ◽  
pp. 259-262 ◽  
Author(s):  
W. Brinkmann ◽  
J. Siebert ◽  
W. Yuan
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Optical Data ◽  
Radio Sources ◽  
Complementary Information ◽  
X Ray ◽  
Physical Conditions ◽  
Γ Ray

Complementary information over a large energy range appears to be the best way to study the class properties of Active Galactic Nuclei (AGN). While radio data provide superior spatial resolution required for the analysis of source structures and their morphology, optical data are a necessary ingredient for the classification of the objects and for the determination of their redshifts. Finally, X-ray (and more recently γ-ray) observations give vital information about the energetics of the central engines and on the physical conditions of the ‘heart of the machine’.

scholarly journals Physical Conditions in Active Galactic Nuclei

1989 ◽  
Vol 134 ◽  
pp. 535-536
Author(s):  
V. S. Artyukh
Keyword(s):  
Magnetic Field ◽  
Synchrotron Radiation ◽  
Active Galactic Nuclei ◽  
Relativistic Electron ◽  
Angular Resolution ◽  
Low Frequency ◽  
Galactic Nuclei ◽  
Radio Sources ◽  
Electron Number ◽  
Physical Conditions

Self-absorption of synchrotron radiation in compact radio sources gives rise to a low-frequency cutoff in their spectra. To study this effect it is necessary to observe the radio sources at meter wavelengths with angular resolution < 1″. Such observations of compact radio sources located in active galactic nuclei lead to estimates of magnetic field strengths and relativistic electron number densities in the AGNs.

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 EVIDENCE FOR INFRARED-FAINT RADIO SOURCES ASz> 1 RADIO-LOUD ACTIVE GALACTIC NUCLEI

2010 ◽  
Vol 710 (1) ◽  
pp. 698-705 ◽  
Author(s):  
Minh T. Huynh ◽  
Ray P. Norris ◽  
Brian Siana ◽  
Enno Middelberg
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Radio Sources

SDSS J154751.94+025550 with double-peaked broad H β but single-peaked broad H α: a candidate for central binary black hole system?

2021 ◽  
Vol 507 (4) ◽  
pp. 5205-5213
Author(s):  
XueGuang Zhang
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
Broad Line ◽  
Line Profiles ◽  
Physical Conditions ◽  
Binary Black Hole ◽  
Sinusoidal Function

ABSTRACT In this manuscript, an interesting blue active galactic nuclei (AGNs) SDSS J154751.94+025550 (=SDSS J1547) is reported with very different line profiles of broad Balmer emission lines: double-peaked broad H β but single-peaked broad H α. SDSS J1547 is the first AGN with detailed discussions on very different line profiles of the broad Balmer emission lines, besides the simply mentioned different broad lines in the candidate for a binary black hole (BBH) system in SDSS J0159+0105. The very different line profiles of the broad Balmer emission lines can be well explained by different physical conditions to two central BLRs in a central BBH system in SDSS J1547. Furthermore, the long-term light curve from CSS can be well described by a sinusoidal function with a periodicity about 2159 d, providing further evidence to support the expected central BBH system in SDSS J1547. Therefore, it is interesting to treat different line profiles of broad Balmer emission lines as intrinsic indicators of central BBH systems in broad line AGN. Under assumptions of BBH systems, 0.125 per cent of broad-line AGN can be expected to have very different line profiles of broad Balmer emission lines. Future study on more broad line AGN with very different line profiles of broad Balmer emission lines could provide further clues on the different line profiles of broad Balmer emission lines as indicator of BBH systems.

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 Supermassive black holes surrounded by dark matter modeled as anisotropic fluid: epicyclic oscillations and their fitting to observed QPOs

2021 ◽  
Vol 2021 (11) ◽  
pp. 059
Author(s):  
Z. Stuchlík ◽  
J. Vrba
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Supermassive Black Holes ◽  
Anisotropic Fluid ◽  
Physical Parameters ◽  
Black Hole Spacetimes ◽  
Test Particles

Abstract Recently introduced exact solution of the Einstein gravity coupled minimally to an anisotropic fluid representing dark matter can well represent supermassive black holes in galactic nuclei with realistic distribution of dark matter around the black hole, given by the Hernquist-like density distribution. For these fluid-hairy black hole spacetimes, properties of the gravitational radiation, quasinormal ringing, and optical phenomena were studied, giving interesting results. Here, using the range of physical parameters of these spacetimes allowing for their relevance in astrophysics, we study the epicyclic oscillatory motion of test particles in these spacetimes. The frequencies of the orbital and epicyclic motion are applied in the epicyclic resonance variant of the geodesic model of quasiperiodic oscillations (QPOs) observed in active galactic nuclei to demonstrate the possibility to solve the cases where the standard vacuum black hole spacetimes are not allowing for explanation of the observed data. We demonstrate that the geodesic model can explain the QPOs observed in most of the active galactic nuclei for the fluid-hairy black holes with reasonable halo parameters.

scholarly journals Inferring the jet parameters of active galactic nuclei using Bayesian analysis of VLBI data with a non-uniform jet model

2019 ◽  
Vol 488 (1) ◽  
pp. 939-953 ◽  
Author(s):  
Ilya N Pashchenko ◽  
Alexander V Plavin
Keyword(s):  
Bayesian Analysis ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Peak Frequency ◽  
Physical Parameters ◽  
Image Deconvolution ◽  
Long Baseline ◽  
Central Engine ◽  
Electron Positron ◽  
Vlbi Data

ABSTRACTThe physical parameters of the jets of active galactic nuclei observed with Very Long Baseline Interferometry (VLBI) are usually inferred from core-shift measurements or from the flux and size measured at the peak frequency of the synchrotron spectrum. Both methods are preceded by modelling the observed VLBI jet structure with simple Gaussian templates. Here we infer the jet parameters using an inhomogeneous jet model directly, bypassing the modelling of the source structure with a Gaussian template or image deconvolution. We apply Bayesian analysis to multifrequency VLBA observations of radio galaxy NGC 315 and find that its parsec-scale jet is well described by an inhomogeneous conical model. Our results favour an electron–positron jet. We also detect a component as a part of a counter jet. Its position implies the presence of an external absorber with a steep density gradient close (r = 0.1 pc) to the central engine.

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