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Kinematic and Thermodynamic Properties of the Galaxy
  • Jeffrey M. La Fortune
Jeffrey M. La Fortune

Corresponding Author:[email protected]

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We present the first detailed physically-based thermodynamic model of the Galaxy as obtained from high-resolution kinematical data from the inner stellar halo. We interpret the observed distribution of Hyper Velocity Stars (HVS) as a physical manifestation of the Maxwell-Boltzmann (M-B) probability distribution expected for a fully virialized galactic system existing in quasi-equilibrium with its surroundings. The conventional view is that the HVS sample originates from chance gravitational encounters that have attained enough speed to escape the Galaxy. We counter that the HVS population is created by thermodynamic effects and link the observed mid-disk velocity peak with the M-B most probable velocity VPeak ≈ Vmp=432 km/s. Most of the HVS population originates at the Galactic virialization radius of 23 kpc with the current observed sample reproducing the M-B distribution with fidelity.