Dark matter dominated dwarf disc galaxy Segue 1

Abstract

Several observations reveal that dwarf galaxy Segue 1 has a dark matter (DM) halo at least ~ 200 times more massive than its visible baryon mass of only ~ 103 solar masses. The baryon mass is dominated by stars with perhaps an interstellar gas mass of < 13 solar masses. Regarding Segue 1 as a dwarf disc galaxy by its morphological appearance of long stretch, we invoke the dynamic model of Xiang-Gruess, Lou & Duschl (XLD) to estimate its physical parameters for possible equilibria with and without an isopedically magnetized gas disc. We estimate the range of DM mass and compare it with available observational inferences. Due to the relatively high stellar velocity dispersion compared to the stellar surface mass density, we find that a massive DM halo would be necessary to sustain disc equilibria. The required DM halo mass agrees grossly with observational inferences so far. For an isopedic magnetic field in a gas disc, the ratio f between the DM and baryon potentials depends strongly on the magnetic field strength. Therefore, a massive DM halo is needed to counteract either the strong stellar velocity dispersion and rotation of the stellar disc or the magnetic Lorentz force in the gas disc. By the radial force balances, the DM halo mass increases for faster disc rotation.

5 pages, 2 figures, accepted for publication in MNRAS

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Cited by in corpus (5)

• Dark Matter and Fundamental Physics with the Cherenkov Telescope Array
• Searches for Dark Matter annihilation signatures in the Segue 1 satellite galaxy with the MAGIC-I telescope
• Direct Constraints on Minimal Supersymmetry from Fermi-LAT Observations of the Dwarf Galaxy Segue 1
• Dark Matter: The evidence from astronomy, astrophysics and cosmology
• Relativistic Self-similar Dynamic Collapses of Black Holes in General Polytropic Spherical Clouds