51st Annual Meeting of the APS Division of Plasma Physics
Volume 54, Number 15
Monday–Friday, November 2–6, 2009;
Atlanta, Georgia
Session UI3: Basic Plasmas: Novel Plasmas in Laboratory and Space
2:00 PM–5:00 PM,
Thursday, November 5, 2009
Room: Centennial II
Chair: Matthew Stoneking, Lawrence University
Abstract ID: BAPS.2009.DPP.UI3.4
Abstract: UI3.00004 : High Energy Plasmas in the Surroundings of Black Holes: Composite Disk Structures and Characteristic Modes$*$
3:30 PM–4:00 PM
Preview Abstract
Abstract
Author:
Bruno Coppi
(MIT)
Theoretically finding of composite disk structures around compact
objects (e.g. black holes) and recent experimental observations
indicate that highly coherent and dynamically important magnetic
field configurations exist in the core of these structures [1].
These coherent configurations provide a means to resolve the
``accretion paradox'' for a magnetized disk [2] while the
formation of jets that are emitted in the close vicinity of the
compact object is related to them. The absence of vigorous
accretion activity in the presence of black holes in old galaxies
can be attributed to the loss of the surrounding coherent
magnetic configurations during their history. As for relevant
dynamics, axisymmetric (ballooning) modes as well as
tri-dimensional spirals can be excited from disks with a ``seed''
magnetic field, under the effects of differential rotation and of
the vertical plasma pressure gradient. The properties of these
spirals are strongly dependent on their vertical structure.
Axisymmetric modes can produce vertical flows of thermal energy
[3] and particles in opposing directions that can be connected to
the winds emanating from disks in Active Galactic Nuclei (AGN's).
A similarity with the effects of temperature gradient driven
modes in magnetically confined laboratory plasmas is pointed out.
Spiral modes that are oscillatory in time and in the radial
direction can produce transport of angular momentum toward the
outer region of the disk structure, a necessary process for the
occurrence of accretion [3]. The excitation of radially localized
density spirals co-rotating with the plasma, at a distance
related to the Schwartzchild radius $R_{S}=2GM_{*}/c^{2}$ where
$M_{*}$ is the black hole mass, is proposed [4] as the
explanation for High Frequency Quasi Periodic Oscillations
(HFQPOs) of non-thermal X-ray emission from compact objects.
$*$Sponsored in part by the U.S. Department of Energy.\\[4pt]
[1] B. Coppi and F. Rousseau \textit{Ap. J.} \textbf{641} 458
(2006)\\[0pt]
[2] B. Coppi to be published in \textit{Pl. Phys. Cont. Fus.}
(2009)\\[0pt]
[3] B. Coppi \textit{Europhys. Letters} \textbf{82} 19001
(2008)\\[0pt]
[4] Coppi B and P. Rebusco, Paper P5.154, EPS Int. Conf. Pl.
Phys. (Crete, Greece, 2008).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.DPP.UI3.4