Talk detail

Participant	Alberti, Giuseppe
Institution	Living Systems Research - Roseggerstraße 27/2 - Klagenfurt am Wörthersee - Kärnten - Austria

Session	DM4	Accepted	Yes	Order	8	Time	17:30	15'
Talk	Oral abstract	Title	On the Dynamic Instability of Self-Gravitating Systems
Coauthors	Merafina, Marco
Abstract	The study of the stabilities of the self-gravitating systems is an old but still active topic of research that can be classified in two main branches, thermodynamic and dynamic. Instabilities of the first type refer to some phenomena such as the gravo-thermal catastrophe in Globular Clusters or the occurrence of gravitational phase transitions in the case of the Fermi gas. Instabilities of the second type, conversely, refer to some problems such as the radial and the non-radial oscillations of the spherical stars. The subject of this work is the study of the rise of the dynamic instabilities by considering the case of anisotropic fluids in a general relativistic framework. In particular, a stability criterion (expressed in terms of the adiabatic local index) is derived. Moreover, some applications of the criterion to the case of some astrophysical systems are shown.
Pdf file

Session	DM4	Accepted	Yes	Order	99	Time
Talk	Poster abstract	Title	Gravitational Phase Transition of Fermionic Matter in a General-relativistic Framework
Coauthors	Chavanis, Pierre-Henri
Abstract	The Thomas-Fermi model at finite temperature is extended to describe a system of self-gravitating massive fermions in a general-relativistic framework. The existence and properties of the gravitational phase transition, in both the canonical and microcanonical ensembles, are investigated numerically. It is shown that, in the canonical ensemble, when a non-degenerate fermionic gas is cooled below a critical temperature, a condensed phase emerges, consisting of quasi-degenerate fermion stars. In the microcanonical ensemble, similarly, a condensed phase emerges when the energy of the system is below a critical value.
Pdf file