Axisymmetric Schwarzschild models of an isothermal axisymmetric mock dwarf spheroidal galaxy
| Autor: | Amina Helmi, Jorrit H. J. Hagen, Maarten A. Breddels |
|---|---|
| Přispěvatelé: | Astronomy |
| Rok vydání: | 2019 |
| Předmět: |
Stellar kinematics
SCULPTOR Dark matter FOS: Physical sciences Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics 01 natural sciences dark matter Flattening FORNAX DSPH GALAXIES 0103 physical sciences KINEMATICS 010306 general physics 010303 astronomy & astrophysics galaxies: kinematics and dynamics Astrophysics::Galaxy Astrophysics ANISOTROPY Physics Velocity dispersion Astronomy and Astrophysics galaxies: dwarf Radius Astrophysics - Astrophysics of Galaxies Galaxy Dwarf spheroidal galaxy MASS PROFILE Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Schwarzschild radius |
| Zdroj: | Astronomy & astrophysics, 632:99. EDP Sciences |
| ISSN: | 1432-0746 0004-6361 |
| DOI: | 10.1051/0004-6361/201936196 |
| Popis: | We test the ability of Schwarzschild's orbit superposition method in measuring the mass content, scale radius and shape of a flattened dwarf spheroidal galaxy. Until now, most dynamical model efforts have assumed that dwarf spheroidal galaxies and their host halos are spherical. We use an Evans model (1993) to construct an isothermal mock galaxy whose properties somewhat resemble those of the Sculptor dwarf spheroidal galaxy. This mock galaxy contains flattened luminous and dark matter components, resulting in a logarithmic profile for the global potential. We have tested how well our Schwarzschild method could constrain the characteristic parameters of the system for different sample sizes, and also if the functional form of the potential was unknown. When assuming the true functional form of the potential, the Schwarzschild modelling technique is able to provide an accurate and precise measurement of the characteristic mass parameter of the system and reproduces well the light distribution and the stellar kinematics of our mock galaxy. When assuming a different functional form for the potential, such as a flattened NFW profile, we also constrain the mass and scale radius to their expected values. However in both cases, we find that the flattening parameter remains largely unconstrained. This is likely because the information content of the velocity dispersion on the geometric shape of the potential is too small, since $\sigma$ is constant across our mock dSph. Our results using Schwarzschild's method indicate that the mass enclosed can be derived reliably, even if the flattening parameter is unknown, and already for samples containing 2000 line-of-sight radial velocities, such as those currently available. Further applications of the method to more general distribution functions of flattened systems are needed to establish how well the flattening of dSph dark halos can be determined. Comment: 13 pages, 14 figures. Comments are welcome |
| Databáze: | OpenAIRE |
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