Sarkar, S and Jog, CJ (2022) Gravitational potential energy of a multicomponent galactic disk. In: Astronomy and Astrophysics, 665 .

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Abstract
We calculate ab initio the gravitational potential energy per unit area for a gravitationally coupled multicomponent galactic disk of stars and gas, which is given as the integration over vertical density distribution, vertical gravitational force, and vertical distance. This is based on the method proposed by Camm for a singlecomponent disk, which we extend here for a multicomponent disk by deriving the expression of the energy explicitly at any galactocentric radius R. For a selfconsistent distribution, the density and force are obtained by jointly solving the equation of vertical hydrostatic equilibrium and the Poisson equation. Substituting the numerical values for the density distribution and force obtained for the coupled system, we find in the derived expression of the energy that the energy of each component remains unchanged compared to the energy for the corresponding singlecomponent case. We explain this surprising result by simplifying the above expression for the energy of a component analytically, which turns out to be equal to the surface density times the squared vertical velocity dispersion of the component. However, the energy required to raise a unit test mass to a certain height z from the midplane is higher in the coupled case. The system is therefore more tightly bound closer to the midplane, and hence it is harder to disturb it due to an external tidal encounter.
Item Type:  Journal Article 

Publication:  Astronomy and Astrophysics 
Publisher:  EDP Sciences 
Additional Information:  The copyright for this article belongs to the Author(s). 
Keywords:  Galaxies; Gravitation; Molecular physics; Potential energy, Density distributions; Galactic disks; Galaxies: Kinematics and dynamics; Galaxies:structure; Galaxy: disks; Gravitational potential energy; Methods:analytical; Multicomponents; Solar neighbourhood, Poisson equation 
Department/Centre:  Division of Physical & Mathematical Sciences > Physics 
Date Deposited:  07 Nov 2022 10:03 
Last Modified:  07 Nov 2022 10:03 
URI:  https://eprints.iisc.ac.in/id/eprint/77772 
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