Astronomy and Astrophysics – Astrophysics – General Relativity and Quantum Cosmology
Scientific paper
2005-10-19
Class. Quant. Grav. 22, 4715-4728 (2005)
Astronomy and Astrophysics
Astrophysics
General Relativity and Quantum Cosmology
13 pages, no figure
Scientific paper
10.1088/0264-9381/22/22/005
We analyze the effects induced by the bulk viscosity on the dynamics associated to the extreme gravitational collapse. Aim of the work is to investigate whether the presence of viscous corrections to the evolution of a collapsing gas cloud influence the fragmentation process. To this end we study the dynamics of a uniform and spherically symmetric cloud with corrections due to the negative pressure contribution associated to the bulk viscosity phenomenology. Within the framework of a Newtonian approach (whose range of validity is outlined), we extend to the viscous case either the Lagrangian, either the Eulerian motion of the system and we treat the asymptotic evolution in correspondence to a viscosity coefficient of the form $\zeta=\zeta_0 \rho^{nu}$ ($\rho$ being the cloud density and $\zeta_0=const.$). We show how, in the adiabatic-like behavior of the gas (i.e. when the politropic index takes values $4/3<\gamma\leq5/3$), density contrasts acquire, asymptotically, a vanishing behavior which prevents the formation of sub-structures. We can conclude that in the adiabatic-like collapse the top down mechanism of structures formation is suppressed as soon as enough strong viscous effects are taken into account. Such a feature is not present in the isothermal-like (i.e. $1\leq\gamma<4/3$) collapse because the sub-structures formation is yet present and outlines the same behavior as in the non-viscous case. We emphasize that in the adiabatic-like collapse the bulk viscosity is also responsible for the appearance of a threshold scale beyond which perturbations begin to increase.
Carlevaro Nakia
Montani Giovanni
No associations
LandOfFree
On the Gravitational Collapse of a Gas Cloud in Presence of Bulk Viscosity does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with On the Gravitational Collapse of a Gas Cloud in Presence of Bulk Viscosity, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On the Gravitational Collapse of a Gas Cloud in Presence of Bulk Viscosity will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-241916