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Universal non-Gaussian velocity distribution in violent gravitational processes.
Osamu Iguchi1, Yasuhide Sota, Takayuki Tatekawa
1Department of Physics, Ochanomizu University, 2-1-1 Ohtuka, Bunkyo, Tokyo 112-8610, Japan. osamu@phys.ocha.ac.jp
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|February 9, 2005
Summary
Violent gravitational processes in astrophysics create universal non-Gaussian velocity distributions, known as the DT distribution. This distribution arises from strong particle mixing and is robust against various initial conditions.
Area of Science:
- Astrophysics
- Cosmology
- Statistical Mechanics
Background:
- Gravitational collapse and cluster collisions are fundamental processes in cosmic structure formation.
- Understanding the velocity distribution of particles in these systems is crucial for interpreting observational data and validating theoretical models.
Purpose of the Study:
- To investigate the velocity distribution in systems undergoing violent gravitational processes, specifically spherical collapses and cluster-pair collisions.
- To identify and characterize any universal statistical properties of these velocity distributions.
Main Methods:
- Utilizing N-body simulations to model the dynamics of spherical collapses and cluster-pair collisions.
- Analyzing the resulting velocity distributions to identify deviations from Gaussian behavior and search for universal patterns.
Main Results:
- The velocity distribution in quasistationary states of violent gravitational processes is generally non-Gaussian.
- A universal non-Gaussian velocity distribution, termed the DT distribution, emerges due to strong particle mixing.
- The DT distribution is a superposition of Gaussian distributions and correlates with energy fluctuations.
Conclusions:
- The DT distribution is a robust feature of systems dominated by violent gravitational processes, independent of initial conditions.
- Coherent motions like radial infall and rotation can suppress the emergence of the DT distribution.
- The findings provide insights into the statistical mechanics of self-gravitating systems and their relation to virial equilibrium and mass-temperature relations.