Iron K fluorescence and high energy bump from accretion disks in AGNs

2005 ◽  
pp. 201-204
Author(s):  
G. Matt ◽  
G. C. Perola ◽  
L. Piro
Keyword(s):  
Accretion Disks ◽  
High Energy

scholarly journals Relativistic Particle Transport in Hot Accretion Disks

1994 ◽  
Vol 142 ◽  
pp. 949-953
Author(s):  
Peter A. Becker ◽  
Menas Kafatos ◽  
Michael Maisack
Keyword(s):  
Black Holes ◽  
Accretion Disks ◽  
Relativistic Particle ◽  
High Energy ◽  
Black Hole Mass ◽  
Radiation Mechanisms ◽  
Accretion Rates ◽  
Inner Region ◽  
Two Temperature ◽  
Intense Radiation

AbstractAccretion disks around rapidly rotating black holes provide one of the few plausible models for the production of intense radiation in AGNs above energies of several hundred MeV. The rapid rotation of the hole increases the binding energy per nucleon in the last stable orbit relative to the Schwarzschild case, and naturally leads to ion temperatures in the range 1012 -1013 K for sub-Eddington accretion rates. The protons in the hot inner region of a steady, two-temperature disk form a reservoir of energy that is sufficient to power the observed EGRET outbursts if the black hole mass is 1010M⊙ . Moreover, the accretion timescale for the inner region is comparable to the observed transient timescale of ~1 week. Hence EGRET outbursts may be driven by instabilities in hot, two-temperature disks around supermassive black holes. In this paper we discuss turbulent (stochastic) acceleration in hot disks as a possible source of GeV particles and radiation. We constrain the model by assuming the turbulence is powered by a collective instability that drains energy from the hot protons. We also provide some ideas concerning new, high-energy Penrose processes that produce GeV emission be directly tapping the rotational energy of Kerr black holes.Subject headings: acceleration of particles — accretion, accretion disks — galaxies: nuclei — quasars: individual (3C 279) — radiation mechanisms: nonthermal

scholarly journals Hot Accretion Disks and the High Energy Background

1983 ◽  
Vol 104 ◽  
pp. 345-346
Author(s):  
M. Kafatos ◽  
Jean A. Eilek
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Spectral Range ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
High Energy ◽  
X Rays ◽  
X Ray

The origin of the high energy (X-ray and gamma-ray) background may be attributed to discrete sources, which are usually thought to be active galactic nuclei (AGN) (cf. Rothschild et al. 1982, Bignami et al. 1979). At X-rays a lot of information has been obtained with HEAO-1 in the spectral range 2–165 keV. At gamma-rays the background has been estimated from the Apollo 15 and 16 (Trombka et al. 1977) and SAS-2 (Bignami et al. 1979) observations. A summary of some of the observations (Rothschild et al. 1982) is shown in Figure 1. The contribution of AGN to the diffuse high energy background is uncertain at X-rays although it is generally estimated to be in the 20–30% range (Rothschild et al. 1982). At gamma-rays, in the range 1–150 MeV, AGN (specifically Seyfert galaxies) could account for all the emission.

scholarly journals The high-energy spectrum of hot accretion disks

1983 ◽  
Vol 271 ◽  
pp. 804 ◽  
Author(s):  
J. A. Eilek ◽  
M. Kafatos
Keyword(s):  
Energy Spectrum ◽  
Accretion Disks ◽  
High Energy

scholarly journals Soft X-rays of AGN: Emission from Accretion Disks?

1997 ◽  
Vol 163 ◽  
pp. 805-806
Author(s):  
R. Staubert ◽  
T. Dörrer ◽  
C. Müller ◽  
P. Friedrich ◽  
H. Brunner
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Galactic Nuclei ◽  
High Energy ◽  
X Rays ◽  
X Ray ◽  
Sky Survey ◽  
High Energy Tail ◽  
Low Energies ◽  
Excess Component

Soft X-ray spectra of many Active Galactic Nuclei (AGN) show structure which suggests excess emission at low energies, mostly below 1 keV. This was confirmed by the ROSAT spectra (0.1–2.4 keV) AGN in our samples which generally have steeper power law spectra than the canonical index of 0.7. The soft excess component may be the high energy tail of the big blue bump which in turn may be due to the integrated emission from an accretion disk around the central black hole.We discuss results of our spectral analysis of two different samples of AGN: 1) QSO/Seyfert-I from the ROSAT All Sky Survey (RASS) and 2) radio-quiet QSO from ROSAT Pointed Observations. The ROSAT data are combined with UV Data from IUE and hard X-ray data from various hard X-ray missions.

scholarly journals Influence of Cosmic Repulsion and Magnetic Fields on Accretion Disks Rotating around Kerr Black Holes

Universe ◽  
2020 ◽  
Vol 6 (2) ◽  
pp. 26 ◽  
Author(s):  
Zdeněk Stuchlík ◽  
Martin Kološ ◽  
Jiří Kovář ◽  
Petr Slaný ◽  
Arman Tursunov
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Magnetic Fields ◽  
Accretion Disks ◽  
Vacuum Energy ◽  
High Energy ◽  
Supermassive Black Holes ◽  
Ultra High Energy ◽  
Thin And Thick Disks ◽  
High Energy Particles

We present a review of the influence of cosmic repulsion and external magnetic fields on accretion disks rotating around rotating black holes and on jets associated with these rotating configurations. We consider both geometrically thin and thick disks. We show that the vacuum energy represented by the relic cosmological constant strongly limits extension of the accretion disks that is for supermassive black holes comparable to extension of largest galaxies, and supports collimation of jets at large distances from the black hole. We further demonstrate that an external magnetic field crucially influences the fate of ionized Keplerian disks causing creation of winds and jets, enabling simultaneously acceleration of ultra-high energy particles with energy up to 10 21 eV around supermassive black holes with M ∼ 10 10 M ⊙ surrounded by sufficiently strong magnetic field with B ∼ 10 4 G. We also show that the external magnetic fields enable existence of “levitating” off-equatorial clouds or tori, along with the standard equatorial toroidal structures, if these carry a non-vanishing, appropriately distributed electric charge.

scholarly journals Two-Temperature Transonic Accretion Disks

1998 ◽  
Vol 188 ◽  
pp. 411-411
Author(s):  
K.E. Nakamura ◽  
M. Kusunose ◽  
R. Matsumoto ◽  
S. Kato
Keyword(s):  
Accretion Disks ◽  
Thermal Structure ◽  
Electron System ◽  
High Energy ◽  
Ion Energy ◽  
X Ray ◽  
Accretion Flows ◽  
High Energy Emission ◽  
Advective Heat Transport ◽  
Two Temperature

The optically thin, advection-dominated accretion flows are thermally stable against global perturbations. In addition, they have high temperatures because of inefficient radiative cooling. They are thus promising candidates of models to explain the high energy emission of X-ray stars and AGNs. So far, models, however, take no account of the advective heat transport in determining the thermal structure of the electron system. The validly of this neglect, however, must be checked by integrating the electron energy equation globally as well as the ion energy one.

scholarly journals High-energy Neutrinos from Choked Gamma-Ray Bursts in Active Galactic Nucleus Accretion Disks

2021 ◽  
Vol 911 (2) ◽  
pp. L19
Author(s):  
Jin-Ping Zhu ◽  
Kai Wang ◽  
Bing Zhang ◽  
Yuan-Pei Yang ◽  
Yun-Wei Yu ◽  
...  
Keyword(s):  
Accretion Disks ◽  
Active Galactic Nucleus ◽  
Gamma Ray ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
High Energy Neutrinos
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