scholarly journals Generation of X-Ray Fluctuations in X-Ray Binaries

1996 ◽  
Vol 158 ◽  
pp. 359-362
Author(s):  
S. Mineshige ◽  
M. Takeuchi ◽  
H. Negoro
Keyword(s):  
Accretion Disks ◽  
Mass Density ◽  
Temporal Distribution ◽  
Critical Value ◽  
Short Term ◽  
X Ray ◽  
Self Organized ◽  
Power Spectral ◽  
Self Organized Criticality ◽  
X Ray Binaries

AbstractShort-term aperiodic fluctuations with 1/f-like power spectral density (PSD), where f is the frequency, are characteristics of X-ray radiation from X-ray binaries. To investigate a mechanism creating fluctuations, we construct a cellular-automaton model for accretion disks based on the concept of self organized criticality (SOC). In this model, mass accretion takes place either by an avalanche triggered when the local mass density exceeds some critical value, or by a gradual diffusion occurring regardless of the critical condition. With this model, we can reproduce the observational PSD, the distributions of peak intensities of X-ray shots, and non-random temporal distribution of the shots. Possible accretion disk models producing l/f-like X-ray fluctuations are discussed. We conclude that such disks are likely to be advection dominated.

scholarly journals Modeling of Oxygen-Neon Dominated Accretion Disks in Ultracompact X-Ray Binaries: 4U 1626-67

2004 ◽  
Vol 194 ◽  
pp. 146-147 ◽  
Author(s):  
K. Werner ◽  
T. Nagel ◽  
S. Dreizler ◽  
T. Rauch
Keyword(s):  
Accretion Disks ◽  
Important Process ◽  
Gravitational Settling ◽  
X Ray ◽  
The Core ◽  
Synthetic Spectra ◽  
First Results ◽  
Low Mass ◽  
X Ray Binaries

AbstractWe report on first results of computing synthetic spectra from H/He-poor accretion disks in ultracompact LMXBs. We aim at the determination of the chemical composition of the very low-mass donor star, which is the core of a former C/O white dwarf. The abundance analysis allows to draw conclusions on gravitational settling in WDs which is an important process affecting cooling times and pulsational g-mode periods.

scholarly journals Magnetically Driven Warping and Precession of Accretion Disks: Implications for Exotic Stellar Variabilities

2002 ◽  
Vol 187 ◽  
pp. 215-220
Author(s):  
Dong Lai
Keyword(s):  
Accretion Disks ◽  
Low Frequency ◽  
Disk Accretion ◽  
X Ray ◽  
T Tauri ◽  
Magnetic Stars ◽  
Low Mass ◽  
Inner Region ◽  
X Ray Binaries

AbstractThe inner region of the accretion disk around a magnetized star is subjected to magnetic torques that induce warping and precession of the disk. These torques arise from interactions between the stellar field and the induced electric currents in the disk. These novel magnetic effects give rise to some “exotic” stellar variabilities, and may play an important role in explaining a number of puzzling behaviors related to disk accretion onto magnetic stars, such as mHz QPOs in X-ray pulsars, long-term periodicities of X-ray binaries (including precession of jets), low-Frequency (10-50 Hz) QPO’s in low-mass X-ray binaries, and photometric variabilities of T Tauri stars.

SELF-ORGANIZED CRITICALITY AND THE BARKHAUSEN EFFECT IN AMORPHOUS AND POLYCRYSTALLINE METALS

1993 ◽  
Vol 07 (01n03) ◽  
pp. 934-937 ◽  
Author(s):  
PAUL J. COTE ◽  
LAWRENCE V. MEISEL
Keyword(s):  
Power Law ◽  
Barkhausen Effect ◽  
Self Organized ◽  
Polycrystalline Metals ◽  
Power Spectral ◽  
Power Spectral Densities ◽  
Spatially Extended ◽  
Self Organized Criticality ◽  
Dissipative Dynamical Systems ◽  
Pulse Energies

An investigation of the possibility that the Barkhausen effect in amorphous and polycrystalline ferromagnets is an example of self-organized criticality is described. Since the theory of self-organized criticality was introduced by Bak, Tang, and Weisenfeld to explain the behavior of spatially extended, dissipative, dynamical systems the Barkhausen effect is a natural candidate for such a description. The data are consistent with self-organized critical behavior: the power spectral densities depend on frequency f as 1/fa and the distribution of pulse energies are well described by a power law analogous to the Gutenberg-Richter law for earthquakes. Alternative explanations for power law dependences are also presented.

The spectra of accretion disks and their application to low-mass X-ray binaries

1987 ◽  
Vol 322 ◽  
pp. 329 ◽  
Author(s):  
Ronald E. Taam ◽  
P. Meszaros
Keyword(s):  
Accretion Disks ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

scholarly journals Non-Linear Resonances in Accretion Disks and QPOs

2004 ◽  
Vol 194 ◽  
pp. 128-129
Author(s):  
Włodek Kluźniak
Keyword(s):  
Black Holes ◽  
Neutron Stars ◽  
Accretion Disk ◽  
Accretion Disks ◽  
High Frequency ◽  
Light Curves ◽  
X Ray ◽  
Non Linear ◽  
Low Mass ◽  
X Ray Binaries

AbstractNon-linear oscillations in the accretion disk are favored as an explanation of high-frequency QPOs observed in the light curves of low-mass X-ray binaries containing neutron stars, black holes, or white dwarfs.

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