Based on the framework of Kaniadakis’ statistics and its related kinetic theory, the Jeans instability for self-gravitational systems in the background of Eddington-inspired Born–Infield (EiBI) gravity is revisited. A dispersion relation generalizing the Jeans modes is derived by modifying the Maxwellian distribution to a family of power law distributions parameterized by the κ parameter. It is established that the κ-deformed Kaniadakis distribution has significant effects on the Jeans modes of the collisionless EiBI-gravitational systems. And as expected, in the limitation κ → 0, the corresponding results for Maxwellian case are recovered. The related result in the present work is valuable for the investigations involving the fields of astrophysics such as neutron stars, accretion disks, and relevant plasma physics, etc.
The effect of ion drag on the pulsational mode of gravitational collapse (PMGC) is investigated within the partially charged dusty plasma model by fluid dynamics. It is found that the ion drag force significantly enhances the instability of the PMGC. In addition, it is shown that the instability of the PMGC is influenced by the ratio of the abundances of charged to neutral grains. These results can be relevant for the planetesimal formation in dark interstellar clouds.
Based on the framework of nonextensive statistics and its related kinetic theory, the Jeans instability in a self-gravitational system composed of dark and bright matters is restudied. The results show that the nonextensivity, the presence of dark matter, has significant effects on the dynamics of Jeans modes. With the increase in the q parameter and the ratio of dispersion velocities, as well as the decreased ratio of densities of dark to bright matters, both critical wave-numbers and growth rates of the instabilities are increased. In addition, as expected, when q → 1, the corresponding results for Maxwellian velocity distribution are recovered. The present results may shed new light on the comprehension of the intrinsic physical mechanism responsible for the collapse of interstellar gas clouds.
The possibility of baryons cooled by a millicharged dark matter (mDM) via mDM-baryons scattering has recently been proposed to explain the observation discrepancy from the Experiment to Detect the Global Epoch of Reionization Signature (EDGES). In this sense, we analyze the Jeans instability of self-gravitational systems in the background of mDM under kinetic regime that the collisionless Boltzmann equation and Poisson equation have been combined to obtain the modified dispersion relation. It is shown that the effect of mDM is significant on the dynamics of gravitational collapse, i.e., the presence of mDM makes the self-gravitational systems more difficult to collapse relatively.
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