Spherical galaxy models as equilibrium configurations in non-extensive statistics

The consideration of galaxies as self-gravitating systems of many collisionless particles allows us to use methods of statistical mechanics for inferring the distribution function of these stellar systems. Actually, the long-range nature of the gravitational force contrasts with the underlying assum...

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Bibliographic Details
Published in:Monthly notices of the Royal Astronomical Society 2011-07, Vol.414 (3), p.2265-2274
Main Authors: Cardone, V. F., Leubner, M. P., Popolo, A. Del
Format: Article
Language:English
Subjects:
Astronomy
Astrophysics
Dark matter
Density
Earth, ocean, space
Entropy
Exact sciences and technology
Formalism
Galaxies
galaxies: kinematic and dynamics
galaxies: spiral
Mathematical analysis
Mathematical models
Stars & galaxies
Statistical analysis
Statistics
Stellar systems
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Summary:The consideration of galaxies as self-gravitating systems of many collisionless particles allows us to use methods of statistical mechanics for inferring the distribution function of these stellar systems. Actually, the long-range nature of the gravitational force contrasts with the underlying assumptions of Boltzmann statistics, where the interactions among particles are assumed to be short-ranged. A particular generalization of the classical Boltzmann formalism is available within the non-extensive context of Tsallis q-statistics, subject to the non-additivity of the entropies of subsystems. Assuming stationarity and isotropy in the velocity space, when solving the generalized collisionless Boltzmann equation it is possible to derive the galaxy distribution function and density profile. We present a particular set of non-extensive models and we investigate their dynamical and observable properties. As a test of the viability of this generalized context, we fit the rotation curve of M33, showing that the proposed approach leads to dark matter haloes in excellent agreement with the observed data.
ISSN:0035-8711
1365-2966
DOI:10.1111/j.1365-2966.2011.18543.x