Shear–free and Homology Conditions for Self–gravitating Dissipative Fluids
نویسندگان
چکیده
The shear free condition is studied for dissipative relativistic self–gravitating fluids in the quasi–static approximation. It is shown that, in the Newtonian limit, such condition implies the linear homology law for the velocity of a fluid element,only if homology conditions are further imposed on the temperature and the emission rate.It is also shown that the shear–free plus the homogeneous expansion rate conditions are equivalent (in the Newtonian limit) to the homology conditions. Deviations from homology and their prospective applications to some astrophysical scenarios are discussed, and a model is worked out.
منابع مشابه
نوسانات آزاد زمین
This work is a study of the Earths free oscillations considering a merge of solid and liquid model. At the turn of 19th century Geophysicists presented the theory of the free oscillations for a self-gravitating, isotropic and compressible sphere. Assuming a steel structure for an Earth size sphere, they predicted a period of oscillation of about 1 hour. About 50 years later, the free oscillat...
متن کاملSpherically Symmetric Dissipative Anisotropic Fluids: a General Study
The full set of equations governing the evolution of self–gravitating spherically symmetric dissipative fluids with anisotropic stresses is deployed and used to carry out a general study on the behaviour of such systems, in the context of general relativity. Emphasis is given to the link between the Weyl tensor, the shear tensor, the anisotropy of the pressure and the density inhomogeneity. In ...
متن کاملLocal stability criterion for self-gravitating disks in modified gravity
We study local stability of self-gravitating fluid and stellar disk in the context of modified gravity theories which predict a Yukawa-like term in the gravitational potential of a point mass. We investigate the effect of such a Yukawa-like term on the dynamics of self-gravitating disks. More specifically, we investigate the consequences of the presence of this term for the local stability of t...
متن کاملStructure and Evolution of Self–gravitating Objects and the Orthogonal Splitting of the Riemann Tensor
The full set of equations governing the structure and the evolution of self–gravitating spherically symmetric dissipative fluids with anisotropic stresses, is written down in terms of five scalar quantities obtained from the orthogonal splitting of the Riemann tensor, in the context of general relativity. It is shown that these scalars are directly related to fundamental properties of the fluid...
متن کامل1 Fragmentation in Kinematically Cold Disks
Gravity is scale free. Thus gravity may form similar structures in self-gravitating systems on different scales. Indeed, observations of the interstellar medium, spiral disks and cosmic structures, reveal similar characteristics. The structures in these systems are very lumpy and inhomo-geneous. Moreover some of these structures do not seem to be of random nature, but obey certain power laws. M...
متن کامل