N-body Self-consistent Stellar-halo Modeling of the Fornax Dwarf Galaxy

Abstract

Abstract We present nearly self-consistent stellar-halo models of the Fornax dwarf spheroidal galaxy associated with the Milky Way galaxy. Such galaxies are dominated by dark matter and have almost no gas in the system. Therefore, they are excellent objects for N-body modeling that takes into account visible and dark matter halo components. In order to model the dark matter halo inferred from the analysis of the measured velocities of Fornax's stars, we constructed several self-consistent quasi-equilibrium models based on two source code sets. One of them (GalactICS Software, NEMO) deals with the self-consistent distribution function modeling that depends on the energy E and vertical component of the angular momentum L z . The other is included in the AGAMA framework and is based on Schwarzschild's calculation of orbits. It can reproduce the nonspherical self-consistent structure of Fornax as the weighted sum of orbit contributions to the galactic density even though the inferred dark halo parameters come from Jeans analysis, which does not require that any distribution functions be positive. To guess the parameters that make the N-body models close to the visible object, we use the stellar dark matter model of the Fornax galaxy based on hydrodynamic axisymmetric Jeans equations taking into account the velocity anisotropy parameter. Then, we studied the evolution of the models by performing N-body simulations with the falcON code in order to test their stability. The variability of the model parameters over time was obtained during simulations. The AGAMA models show the best agreement of the resulting velocity dispersion profiles with the observed data.