Dark matter dominated dwarf disc galaxy Segue 1

作者：Xiang Gruess Meng^*; Lou Yu Qing; Duschl Wolfgang J

来源：Monthly Notices of the Royal Astronomical Society, 2009, 400(1): L52-L56.

DOI：10.1111/j.1745-3933.2009.00761.x

• MHD
• waves
• magnetic fields
• galaxies: haloes
• galaxies: ISM
• galaxies: kinematics and dynamics

Several observations reveal that dwarf galaxy Segue 1 has a dark matter (DM) halo at least similar to 200 times more massive than its visible baryon mass of only similar to 10(3) M(circle dot). The baryon mass is dominated by stars with perhaps an interstellar gas mass of less than or similar to 13 M(circle dot). 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.

• 出版日期2009-11-21
• 单位中国科学院国家天文台