arXiv subjects

Jiulin Du

Publications and source records attributed to Jiulin Du.

81 records · Page 5Linked to original sources

arXiv2007

Nonextensivity and the power-law distributions for the systems with self-gravitating long-range interactions

By a natural nonextensive generalization of the conservation of energy in the q-kinetic theory, we study the nonextensivity and the power-law distributions for the many-body systems with the self-gravitating long-range interactions. It is shown that the power-law distributions describe the long-range nature of the interactions and the non-local correlations within the self-gravitating system with the inhomogeneous velocity dispersion. A relation is established between the nonextensive parameter q and the measurable quantities of the self-gravitating system: the velocity dispersion and the mass density. Correspondingly, the nonextensive parameter q can be uniquely determined from the microscopic dynamical equation and thus the physical interpretation of q different from unity can be clearly presented. We derive a nonlinear differential equation for the radial density dependence of the self-gravitating system with the inhomogeneous velocity dispersion, which can correctly describe the density distribution for the dark matter in the above physical situation. We also apply this q-kinetic approach to analyze the nonextensivity of self-gravitating collisionless systems and self-gravitating gaseous dynamical systems, giving the power-law distributions the clear physical meaning.

cond-mat.stat-mech↗

arXiv2006

The kappa parameter and kappa-distribution in kappa-deformed statistics for the systems in an external field

The kappa-deformed statistics has been studied in many papers. It is naturally important question for us to ask what should the kappa parameter stand for and under what physical situation should the kappa-deformed statistics be suitable for the statistical description of a system. In this paper, we have derived a formula expression of kappa parameter based on the kappa-H theorem, the kappa-velocity distribution and the generalized Boltzmann equation in the framework of kappa-deformed statistics. We thus obtain a physical interpretation for the kappa parameter different from zero with regard to the temperature gradient and the external force field. We show that, as the q-statistics based on Tsallis entropy, the kappa-deformed statistics may also be the candidate one suitable for the statistical description of the systems in external fields when being in the nonequilibrium stationary state, but has different physical characteristics. Namely, the kappa-distribution is found to describe the nonequilibrium stationary state of the system where the external force should be vertical to the temperature gradient.

cond-mat.stat-mech↗

arXiv2006

The Chandrasekhar condition of the equilibrium and stability for a star in the nonextensive kinetic theory

The idea of Chandrasekhar condition of the equilibrium and stability for a star is revisited in the nonextensive kinetic theory based on Tsallis entropy. A new analytical formula generalizing the Chandrasekhar condition is derived by assuming that the stellar matter is kinetically described by the generalized Maxwell-Boltzmann distribution in Tsallis statistics. It is found that the maximum radiation pressure allowed at the center of a star of a given mass is dependent on the nonextensive parameter q. The Chandrasekhar condition in the Maxwellian sense is recovered from the new condition in the case of q=1.

astro-ph↗

arXiv2006

Test of Nonextensive Statistical Mechanics by Solar Sound Speeds

To check the validity of the theory of nonextensive statistical mechanics, we have investigated the nonextensive degree of the solar interior and have tried to find the experimental evidence by helioseismological measurements that q is different from unity. We are able to derive a parameter for providing a lower limit to the nonextensive degree inside the sun that can be uniquely determined by the solar sound speeds measured by helioseismology. After calculating the parameter by using the solar sound speeds, we get the lower limit of(1-q)not less than 0.1902 for all solar radii between 0.15R(sun) and 0.95R(sun) and (1-q)approximately equal to 0.4 for the out layers extending from 0.75R(sun)to 0.95R(sun).Thus, the result that the nonextensive parameter q is significantly different from unity has received the support by the experiment measurements for the solar sound speeds in the helioseismology.

cond-mat.stat-mech↗

arXiv2005

The hydrostatic equilibrium and Tsallis equilibrium for self-gravitating systems

Self-gravitating systems are generally thought to behavior non-extensively due to the long-range nature of gravitational forces. We obtain a relation between the nonextensive parameter q of Tsallis statistics, the temperature gradient and the gravitational potential based on the equation of hydrostatic equilibrium of self-gravitating systems. It is suggested that the nonextensive parameter in Tsallis statistics has a clear physical meaning with regard to the non-isothermal nature of the systems with long-range interactions and Tsallis equilibrium distribution for the self-gravitating systems describes the property of hydrostatic equilibrium of the systems.

astro-ph↗

arXiv2004

The nonextensive parameter and Tsallis distribution for self-gravitating systems

The properties of the nonextensive parameter q and the Tsallis distribution for self-gravitating systems are studied. A mathematical expression of q is deduced based on the generalized Boltzmann equation, the q-H theorem and the generalized Maxwellian q-velocity distribution in the framework of Tsallis statistics. We obtain a clear understanding of the physics of q different from unity with regard to the temperature gradient and the gravitational potential of the self-gravitating systems. It is suggested that the Tsallis statistics could be statistics suitable for describing the nonequilibrium systems with inhomogeneous temperature and the long-range interactions.

cond-mat.stat-mech↗

arXiv2004

Nonextensivity in nonequilibrium plasma systems with Coulombian long-range interactions

The nonextensivity in a non-isothermal plasma system with the Coulombian long-range interactions is studied in the framework of Tsallis statistics. We present for first time a mathematical expression of the nonextensive parameter q based on the mathematical theory about the generalized Boltzmann equation and the q-H theorem and the Maxwellian q-velocity distribution. We obtain a new physical explanation for q concerning the nature of non-isothermal configurations in plasma systems with Coulombian long-range interactions. We also provide one illustration for Almeida theorem (Physica A 300(2001)424) from the kinetic analyses of plasma systems, which means that Tsallis statistics might be a suitable statistics for the description of a nonequilibrium system with a temperature gradient in it.

cond-mat.stat-mech↗

arXiv2004

Jeans criterion in nonextensive statistical mechanics

The Jeans gravitational instability in nonextensive statistical mechanics is studied and a general form of the generalized Jeans criterion is obtained that is related to the q-function . In this approach, the nonextensive model of classical ideal gas is applied to the Jeans problem instead of the ordinary one in extensive statistical mechanics and the generalized critical wavelength to describe the gravitational instability is deduced. This nonextensive modification of the Jeans criterion leads to a new critical length that depends not only on the nonextensive parameter q but also on the dimension D and the total particle numbers N of the system. When, the Jeans length is perfectly recovered. We also give the nonextensive parameter q a physical interpretation that represents an isothermal process of the gas, corresponding to the state of complete mixing, but 0< q <1 is nonisothermal, corresponding to the state of incomplete mixing, it measures the degree of mixing.

astro-ph↗

arXiv2004

Jeans criterion and nonextensive velocity distribution function in kinetic theory

The effect of nonextensivity of self-gravitating systems on the Jeans criterion for gravitational instability is studied in the framework of Tsallis statistics. The nonextensivity is introduced in the Jeans problem by a generalized q-nonextensive velocity distribution function through the equation of state of ideal gas in nonextensive kinetic theory. A new Jeans criterion is deduced with a factor that, however, differs from that one in Ref.[21] and new results of gravitational instability are analyzed for the nonextensive parameter q. An understanding of physical meaning of q and a possible seismic observation to find astronomical evidence for a value of q different from unity are also discussed.

astro-ph↗