DM4 - Self Gravitating Systems and Dark Matter |
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Speaker |
Piscicchia, Kristian |
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Coauthors |
M. Merafina |
| Talk Title |
Gravity and Thermodynamics in globular clusters. Gravothermal instability and some observational evidences |
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Abstract |
This work deals with the consequences which follow from the construction of a selfconsistent thermodynamical model of globular cluster. In so doing we are driven by the necessity of a star cluster model with density and pressure vanishing in correspondence of the surface of the system, whose finite radius is determined by the tidal force of the Galaxy. Considering the evolution of the selfgravitating system and proceeding through infinite equilibrium states, given by reversible transformations, lead us to the introduction of an effective potential term, in the single particle Hamiltonian, taking into account the presence of the kinetic cutoff energy. The influence of the effective potential on the virial theorem will be described, together with the related consequences on the gravothermal stability limits for star clusters, and explored through the series of equilibrium configurations method. The presence of the effective potential in the description of the equilibrium models leads to some observational features, allowing to test the result regarding the critical value connected with the gravothermal instability through the analysis of the W0-distribution. The mean age of Milky Way sample, compared to dynamical time-scales, is sufficiently high so that most of the objects reached the gravothermal instability making the maximum of the distribution coinciding with the critical point. |
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