On the Heating of AGN Magnetospheres

The Langmuir–Landau-Centrifugal Drive (LLCD), which can effectively “convert” gravitational energy into particles, is explored as a driving mechanism responsible for the extreme thermal luminosity acquired by some active galactic nuclei (AGN). For this purpose, we consider equations governing the process of heating of AGN magnetospheres. In particular, we examine the Fourier components of the momentum equation, the continuity equation and the Poisson equation in the linear approximation and estimate the growth rate of the centrifugally excited electrostatic waves and the increment of the Langmuir collapse. It is shown that the process of energy pumping is composed of three stages: in the first stage the energy is efficiently transferred from rotation to the electrostatic modes. In due course of time, the second regime-the Langmuir collapse-occurs, when energy pumping is even more efficient. This process is terminated by the Landau damping, when enormous energy is released in the form of heat. We show that the magnetospheres of the supermassive black holes with luminosities of the order of 1045−46 erg/s can be heated up to 106−10 K.

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Physical Conditions in the Central Region, and the Nature of the Engine

Highlights of Astronomy ◽

10.1017/s1539299600005529 ◽

1983 ◽

Vol 6 ◽

pp. 511-524 ◽

Cited By ~ 1

Author(s):

A. Cavaliere

Keyword(s):

Active Galactic Nuclei ◽

Radiation Source ◽

Galactic Nuclei ◽

Primary Source ◽

Gravitational Energy ◽

Characteristic Change ◽

Cosmological Time ◽

Compact Mass ◽

Physical Conditions ◽

Prime Movers

AbstractThe phenomena associated with Active Galactic Nuclei raise three main astrophysical problems: (1) the nature of the primary source of energy; (2) the physical conditions within the radiation source; (3) the nature of the population evolution over cosmological time-scales.I shall outline the links between (1) and (2), (1) and (3), that briefly go as follows. The Prime Mover is very likely to be a converter of gravitational energy in a very compact mass configuration. The associated radiation source, if it is also very compact, is so efficient and loss-dominated as to require specific conditions for the power transport and supply to the radiating particles: collisionless, effected by electromagnetic fields coherent on scales collective or macroscopic, to the point of producing at times anisotropic bulk motions. Very compact Prime Movers working at high regimes need also a compact mass supply; the output from these compound engines undergoes a characteristic change that accounts for the type of population evolutions of the associated sources.

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Active Galactic Nuclei: Variability at Many Wavelengths

Highlights of Astronomy ◽

10.1017/s1539299600018840 ◽

1998 ◽

Vol 11 (2) ◽

pp. 808-811

Author(s):

Thierry J.-L. Courvoisier

Keyword(s):

Black Hole ◽

Active Galactic Nuclei ◽

Thermal Emission ◽

Galactic Nuclei ◽

Gravitational Energy ◽

Heating Process ◽

Massive Black Hole ◽

Ultraviolet Emission ◽

X Ray ◽

Accretion Process

Active Galactic Nuclei (AGN) are thought to be powered by accretion onto a massive black hole. Understanding how gravitational energy freed by the infall of matter into the black hole is transferred to the radiating regions of the nucleus is one of the main challenges of AGN research. The question is made very complex by the presence of several cooling mechanisms with very diverse physical properties: We observe synchrotron radiation, thermal emission from hot dust, possibly thermal optical and ultraviolet emission and Comptonization processes in the X-ray domain. For each component the radiation is a signature of the cooling process rather than of the heating process. It is our hope that by observing the links and correlations between the emission of the different components we will be able to understand how they are interrelated and how they get their energy supply from the accretion process.

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Relation between winds and jets in radio-loud AGN

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935205 ◽

2019 ◽

Vol 625 ◽

pp. A25 ◽

Cited By ~ 8

Author(s):

Missagh Mehdipour ◽

Elisa Costantini

Keyword(s):

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Inverse Correlation ◽

Field Configuration ◽

Accretion Disc ◽

Driving Mechanism ◽

Significant Inverse Correlation ◽

X Ray ◽

Ejection Mechanism ◽

The Magnetic Field

We have investigated the relation between the two modes of outflow (wind and jet) in radio-loud active galactic nuclei (AGN). For this study we have carried out a systematic and homogeneous analysis of XMM-Newton spectra of a sample of 16 suitable radio-loud Seyfert-1 AGN. The ionised winds in these AGN are parameterised through high-resolution X-ray spectroscopy and photoionisation modelling. We discover a significant inverse correlation between the column density NH of the ionised wind and the radio-loudness parameter R of the jet. We explored different possible explanations for this NH-R relation and find that ionisation, inclination, and luminosity effects are unlikely to be responsible for the observed relation. We argue that the NH-R relation is rather a manifestation of the magnetic driving mechanism of the wind from the accretion disc. Change in the magnetic field configuration from toroidal to poloidal, powering either the wind or the jet mode of the outflow, is the most feasible explanation for the observed decline in the wind NH as the radio jet becomes stronger. Our findings provide evidence for a wind-jet bimodality in radio-loud AGN and shine new light on the link between these two modes of outflow. This has far-reaching consequences for the accretion disc structure and the wind ejection mechanism.

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8.12. MHD accretion in a black hole magnetosphere

Symposium - International Astronomical Union ◽

10.1017/s0074180900085259 ◽

1998 ◽

Vol 184 ◽

pp. 367-368

Author(s):

M. Takahashi

Keyword(s):

Black Hole ◽

Active Galactic Nuclei ◽

Thermal Effects ◽

Galactic Nuclei ◽

Plasma Source ◽

Gravitational Energy ◽

Massive Black Hole ◽

Plasma Sources ◽

Strong Gravitation ◽

The Ideal

To explain the activity of active galactic nuclei or compact X-ray sources, I consider a black hole magnetosphere in the center of these objects. The considering black hole magnetosphere is composed of a massive black hole with surrounding fluids and magnetic fields, and rotates rapidly. Because of the strong gravitation and the rapid rotation, both an accretion and a wind/jet would be generated from plasma sources (e.g., an accretion disk and its corona). The outgoing flow carries the angular momentum from the plasma source effectively, and then the accretion would go on stationary, releasing its gravitational energy. I assume that the magnetosphere is stationary and axisymmetric, and that the ideal MHD approximation is available for the streaming fluid. I discuss the thermal effects on MHD flows, and then I argue that the trans-fast MHD accretion solution can be broken by highly thermal effects.

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