scholarly journals The revived Penrose process can power the central engine in active galactic nuclei

1986 ◽  
Vol 119 ◽  
pp. 395-398
Author(s):  
Sanjay M. Wagh ◽  
N. Dadhich
Keyword(s):  
Magnetic Field ◽  
Active Galactic Nuclei ◽  
Extraction Efficiency ◽  
Galactic Nuclei ◽  
High Energy ◽  
Energy Extraction ◽  
Central Engine ◽  
Penrose Process ◽  
The Magnetic Field ◽  
Very High

Using the fact that the efficiency of the revived (Wagh et al 1985) Penrose process of energy extraction from black holes immersed in electromagnetic fields can be very high (Parthasarathy et al, 1986) we show that this process can comfortably power the ‘central engine’ in Active Galactic Nuclei. The microphysical Penrose process energized particles will be ultrarelativistic in the asymptotic frame. Hence the kinematical analysis of escaping photons by Piran and Shaham (1977) will be a good approximation to the kinematics of these particles. From this analysis one expects the energized particles to emerge within an angle∼ 40° above and below the equatorial plane. These energetic particles, which are collimated in the funnel of an accretion disk and further on by the magnetic field, then, form supersonic, relativistic, bilateral jets. The relativistic Y factor for such jets can be expected to be ∼ 2 since these ultrarelativistic particles will effectively mimick radiation in ‘dragging’ the matter already injected inside the funnel. Various implications of high energy extraction efficiency are illustrated.

scholarly journals Monitoring the Extragalactic High Energy Sky

Galaxies ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 9 ◽  
Author(s):  
Jean-Philippe Lenain
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
High Energy ◽  
Line Of Sight ◽  
Data Sets ◽  
High Energies ◽  
Multi Wavelength ◽  
Rich Data ◽  
Very High

Blazars are jetted active galactic nuclei with a jet pointing close to the line of sight, hence enhancing their intrinsic luminosity and variability. Monitoring these sources is essential in order to catch them flaring and promptly organize follow-up multi-wavelength observations, which are key to providing rich data sets used to derive e.g., the emission mechanisms at work, and the size and location of the flaring zone. In this context, the Fermi-LAT has proven to be an invaluable instrument, whose data are used to trigger many follow-up observations at high and very high energies. A few examples are illustrated here, as well as a description of different data products and pipelines, with a focus given on FLaapLUC, a tool in use within the H.E.S.S. collaboration.

scholarly journals DO ACTIVE GALACTIC NUCLEI CONVERT DARK MATTER INTO VISIBLE PARTICLES?

2008 ◽  
Vol 23 (16) ◽  
pp. 1151-1159 ◽  
Author(s):  
A. A. GRIB ◽  
YU. V. PAVLOV
Keyword(s):  
Black Hole ◽  
Dark Matter ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
High Energy ◽  
Grand Unification ◽  
Ultra High Energy ◽  
High Energy Cosmic Rays ◽  
Opposite Process ◽  
Penrose Process

The hypothesis that dark matter consists of superheavy particles with the mass close to the Grand Unification scale is investigated. These particles were created from vacuum by the gravitation of the expanding Universe and their decay led to the observable baryon charge. Some part of these particles with the lifetime larger than the time of breaking of the Grand Unification symmetry became metastable and survived up to the modern time as dark matter. However, in active galactic nuclei due to large energies of dark matter particles swallowed by the black hole and the possibility of the Penrose process for rotating black hole the opposite process can occur. Dark matter particles become interacting. Their decay on visible particles at the Grand Unification energies leads to the flow of ultra high energy cosmic rays observed by the Auger group. Numerical estimates of the effect leading to the observable numbers are given.

scholarly journals Magnetized black hole as an accelerator of charged particle

2021 ◽  
Author(s):  
Bobur Turimov
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Charged Particle ◽  
Active Galactic Nuclei ◽  
Zeeman Effect ◽  
Galactic Nuclei ◽  
X Ray ◽  
Fundamental Frequencies ◽  
The Magnetic Field ◽  
Relativistic Particles

Astrophysical accretion processes near the black hole candidates, such as active galactic nuclei (AGN), X-ray binary (XRB), and other astrophysical sources, are associated with high-energetic emission of radiation of relativistic particles and outflows (winds and/or jets). It is widely believed that the magnetic field plays a very important role to explain such high energetic processes in the vicinity of those astrophysical sources. In the present research note, we propose that the black hole is embedded in an asymptotically uniform magnetic field. We investigate the dynamical motion of charged particles in the vicinity of a weakly magnetized black hole. We show that in the presence of the magnetic field, the radius of the innermost stable circular orbits (ISCO) for a charged particle is located close to the black hole’s horizon. The fundamental frequencies, such as Keplerian and epicyclic frequencies of the charged particle are split into two parts due to the magnetic field, as an analog of the Zeeman effect. The orbital velocity of the charged particle measured by a local observer has been computed in the presence of the external magnetic field. We also present an analytical expression for the four-acceleration of the charged particle orbiting around black holes. Finally, we determine the intensity of the radiating charged accelerating relativistic particle orbiting around the magnetized black hole.

THE PARSEC-SCALE CIRCULAR POLARIZATION OF ACTIVE GALACTIC NUCLEI AT 22 AND 15 GHZ

2008 ◽  
Vol 17 (09) ◽  
pp. 1531-1535 ◽  
Author(s):  
V. M. VITRISHCHAK ◽  
D. C. GABUZDA
Keyword(s):  
Magnetic Field ◽  
Active Galactic Nuclei ◽  
Circular Polarization ◽  
Galactic Nuclei ◽  
Core Region ◽  
Field Orientation ◽  
Magnetic Field Orientation ◽  
Long Baseline ◽  
Very Long Baseline Array ◽  
The Magnetic Field

We present the results of parsec-scale circular polarization measurements based on Very Long Baseline Array data for a number of radio-bright, core-dominated active galactic nuclei obtained simultaneously at 22 and 15 GHz. The degrees of circular polarization mc for the VLBI core region at 15 GHz are similar to values reported earlier at this wavelength, with typical values of a few tenths of a percent. The origin of this polarization is almost certainly the conversion of linear to circular polarization during the propagation of the radiation through a magnetised plasma. We find that mc is as often higher as lower at the higher frequency, for reasons that are not clear. Our results confirm the earlier finding that the sign of the circular polarization at a given observing frequency is generally consistent across epochs separated by several years or more, suggesting stability of the magnetic field orientation in the innermost jets.

scholarly journals Similarity and diversity of black holes - view from the Very High Energies

2016 ◽  
Vol 12 (S324) ◽  
pp. 11-18
Author(s):  
Elina Lindfors
Keyword(s):  
Black Holes ◽  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
High Energy ◽  
Mass Scale ◽  
Relativistic Jets ◽  
Very High Energy ◽  
Energy Gamma ◽  
Very High

AbstractActive galactic nuclei, hosting supermassive black holes and launching relativistic jets, are the most numerous objects on the gamma-ray sky. At the other end of the mass scale, phenomena related to stellar mass black holes, in particular gamma-ray bursts and microquasars, are also seen on the gamma-ray sky. While all of them are thought to launch relativistic jets, the diversity even within each of these classes is enormous. In this review, I will discuss recent very high energy gamma-ray results that underline both the similarity of the black hole systems, as well as their diversity.

scholarly journals SSC SCENARIO FOR TEV EMISSION FROM NON-BLAZAR AGNs

2008 ◽  
Vol 17 (09) ◽  
pp. 1577-1584
Author(s):  
J.-P. LENAIN ◽  
C. BOISSON ◽  
H. SOL
Keyword(s):  
Active Galactic Nuclei ◽  
Large Scale ◽  
Galactic Nuclei ◽  
High Energy ◽  
Jet Formation ◽  
Extragalactic Source ◽  
Very High Energy ◽  
Magnetohydrodynamic Simulations ◽  
High Energy Emission ◽  
Very High

M 87 is the first extragalactic source detected in the TeV γ-ray domain that is not a blazar, its large scale jet not being aligned to the line of sight. We present here a multi-blob synchrotron self-Compton model accounting explicitly for large viewing angles and moderate Lorentz factors as inferred from magnetohydrodynamic simulations of jet formation, motivated by the detection of M 87 at very high energies (VHE; E > 100 GeV ). Predictions are presented for the very high-energy emission of active galactic nuclei with extended optical or X-ray jet, which could be misaligned blazars but still show some moderate beaming. We include predictions for 3C 273, Cen A and PKS 0521–36.

Very High Energy γ-rays from AGN

2002 ◽  
Vol 19 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Tadashi Kifune
Keyword(s):  
Electromagnetic Radiation ◽  
Active Galactic Nuclei ◽  
Energy Band ◽  
Galactic Nuclei ◽  
High Energy ◽  
Current Status ◽  
Very High Energy ◽  
Γ Rays ◽  
Γ Ray ◽  
Very High

AbstractEvidence of TeV γ-ray emission has been found for only a handful of active galactic nuclei, with detailed investigations limited to the blazars Mrk 421 and Mrk 501. TeV γ-ray astronomy, as the highest energy band, provides important information that is hard to obtain from longer wavelength electromagnetic radiation. The current status of TeV γ-ray studies of active galactic nuclei is summarized and our understanding of the high energy phenomena taking place in active galactic nuclei is outlined, with the prospects for future TeV γ-ray observations also considered.

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