Effect of rotation on gravitational instability of optically thick magnetized quantum plasma in the presence of radiation

2018 ◽  
Author(s):  
A. Kumar ◽  
R. K. Pensia
Keyword(s):  
Gravitational Instability ◽  
Quantum Plasma

Effect of spin-induced magnetization and Hall current on self-gravitational instability of magnetized viscous quantum plasma

2014 ◽  
Vol 81 (2) ◽  
Author(s):  
Prerana Sharma ◽  
R. K. Chhajlani
Keyword(s):  
Gravitational Instability ◽  
Quantum Effect ◽  
Normal Mode Analysis ◽  
Longitudinal Direction ◽  
Transverse Mode ◽  
Mode Analysis ◽  
Quantum Plasma ◽  
Longitudinal Modes ◽  
Jeans Criterion ◽  
Basic Equations

The Jeans self-gravitational instability is studied for dense quantum viscous plasma with Hall term and intrinsic magnetization generated by collective electron spin. The quantum magnetohydrodynamic model is employed to formulate the basic equations of the problem. The dispersion relation is obtained using the normal mode analysis, and further reduced for both transverse and longitudinal modes of propagation. The transverse mode of propagation is found to be unaffected by the Hall term but affected by quantum effect, viscosity, and magnetization parameters. The Jeans criterion of instability in the transverse direction is modified by Alfven velocity, magnetization parameter, and quantum effect. The non-gravitating magnetized mode is obtained in the longitudinal direction, which is modified by Hall parameter and is not affected by quantum term, whereas the gravitational mode is unaffected by the magnetization parameter but affected by viscosity and quantum parameters. It is observed that the Jeans condition of instability is affected by the quantum term. The growth rate of Jeans instability is plotted for various values of magnetization, quantum, and viscosity parameters of the quantum plasma medium.

Gravitational instability of rotating magnetized quantum anisotropic plasma

2017 ◽  
Vol 83 (2) ◽  
Author(s):  
Shraddha Argal ◽  
Anita Tiwari ◽  
R. P. Prajapati ◽  
P. K. Sharma
Keyword(s):  
Gravitational Instability ◽  
Fluid Model ◽  
Longitudinal Mode ◽  
Instability Criterion ◽  
Quantum Plasma ◽  
Uniform Rotation ◽  
Longitudinal Modes ◽  
Stabilizing Effect ◽  
Jeans Instability ◽  
Transverse Propagation

The present problem deals with the study of gravitational (Jeans) instability of magnetized, rotating, anisotropic plasmas considering quantum effects. The basic equations of the considered system are constructed using combined Chew–Goldberger–Low (CGL) fluid model and quantum magnetohydrodynamic (QMHD) fluid model. A dispersion relation is obtained using the normal mode technique which is discussed for transverse and longitudinal modes of propagation. It is found that a rotating quantum plasma influences the gravitational mode in transverse propagation but not in longitudinal propagation. The presence of rotation decreases the critical wavenumber and it has a stabilizing effect on the Jeans instability criterion of magnetized quantum plasma in transverse propagation. The firehose instability is unaffected due to the presence of uniform rotation and quantum corrections. We observe from the numerical analysis that region of instability and critical Jeans wavenumber are both decreased due to the presence of uniform rotation. The stabilizing influence of uniform rotation is observed for magnetized, rotating, anisotropic plasmas in the presence of quantum correction. In the case of a longitudinal mode of propagation we found the Jeans instability criterion is not affected by rotation. The quantum diffraction term has a stabilizing effect on the growth rate of the Jeans instability when the wave propagates along the direction of the magnetic field.

Jeans self gravitational instability of strongly coupled quantum plasma

2014 ◽  
Vol 21 (7) ◽  
pp. 072104 ◽  
Author(s):  
Prerana Sharma ◽  
R. K. Chhajlani
Keyword(s):  
Gravitational Instability ◽  
Quantum Plasma ◽  
Strongly Coupled

Saturation mechanism and generated viscosity in gravito-turbulent accretion disks

2020 ◽  
Vol 640 ◽  
pp. A53
Author(s):  
L. Löhnert ◽  
S. Krätschmer ◽  
A. G. Peeters
Keyword(s):  
Growth Rate ◽  
Numerical Simulations ◽  
Accretion Disks ◽  
Gravitational Instability ◽  
Turbulent Viscosity ◽  
Radial Distance ◽  
Maximum Growth ◽  
Wave Number ◽  
Radiative Cooling ◽  
Mixing Length

Here, we address the turbulent dynamics of the gravitational instability in accretion disks, retaining both radiative cooling and irradiation. Due to radiative cooling, the disk is unstable for all values of the Toomre parameter, and an accurate estimate of the maximum growth rate is derived analytically. A detailed study of the turbulent spectra shows a rapid decay with an azimuthal wave number stronger than ky−3, whereas the spectrum is more broad in the radial direction and shows a scaling in the range kx−3 to kx−2. The radial component of the radial velocity profile consists of a superposition of shocks of different heights, and is similar to that found in Burgers’ turbulence. Assuming saturation occurs through nonlinear wave steepening leading to shock formation, we developed a mixing-length model in which the typical length scale is related to the average radial distance between shocks. Furthermore, since the numerical simulations show that linear drive is necessary in order to sustain turbulence, we used the growth rate of the most unstable mode to estimate the typical timescale. The mixing-length model that was obtained agrees well with numerical simulations. The model gives an analytic expression for the turbulent viscosity as a function of the Toomre parameter and cooling time. It predicts that relevant values of α = 10−3 can be obtained in disks that have a Toomre parameter as high as Q ≈ 10.

DIELECTRIC RESPONSE AND ENERGY LOSS FOR AN INTERMEDIATE QUANTUM PLASMA

1979 ◽  
Vol 40 (C7) ◽  
pp. C7-513-C7-514
Author(s):  
N. E. Frankel ◽  
K. C. Hines ◽  
R. D.B. Speirs
Keyword(s):  
Energy Loss ◽  
Dielectric Response ◽  
Quantum Plasma
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