The Fornax Dwarf Galaxy Structure According to the Dark Matter Dominated Self-Consistent Modelling
https://doi.org/10.56304/S2079562920060524
Abstract
A nearly self-consistent quasi-equilibrium stellar halo model is presented for the Fornax dwarf spheroidal satellite galaxy, associated with the Milky Way. Such satellite galaxies are dominated by dark matter and have almost no gas in the system. They are excellent objects for N-body modeling that takes into account visible and dark matter halo components. Each one of the N particles in our model follows its own orbital motion within the self-consistent gravitational potential, which is itself generated by all these particles. A source code is applied that is embedded in the AGAMA framework and is based on the Schwarzschild calculation of orbits. To construct the components, the initial guess is to use a stellar–dark matter model of the Fornax galaxy, which is based on the hydrodynamic axisymmetric Jeans equations, taking into account the velocity anisotropy parameter. The first studies of the galaxy are bounded by the hydrodynamic approaches based on the Jeans equations. However, the free paths of dark matter particles are huge; hence, the applicability of the hydrodynamic approximation is doubtful. Further studies of the dwarf spheroidal galaxies associated with the Milky Way assume non-self-consistent (stars moving in the dark matter gravitational field) models of the objects based on distribution functions depending on the action integrals. Self-consistent modeling is performed only for the spherically symmetric approximation. Our model is self-consistent and axially symmetric; i.e., it takes into account the prolateness of the dark halo. On the basis of the available density distribution of the components, we obtain the model velocity dispersion profile of the galaxy’s stellar component. The profile is consistent with the observational data for the stellar component. Thus, the given density distribution for the dark halo can be used to predict the dark matter annihilation signal. Calculations are also performed for the numerical evolution of the resulting model in a self-consistent N-body gravitational field. The model is shown to be sufficiently stable over several dozen dynamical times.
About the Author
G. A. Shchelkanova
National Research Centre “Kurchatov Institute”
Russian Federation
Russian Federation
G. A. Shchelkanova,
Moscow, 123182.
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Review
For citations:
Shchelkanova G.A. The Fornax Dwarf Galaxy Structure According to the Dark Matter Dominated Self-Consistent Modelling. Nuclear Physics and Engineering. 2021;12(4):207-213. (In Russ.) https://doi.org/10.56304/S2079562920060524
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