Velocity Dispersion Profiles of Seven Dwarf Spheroidal Galaxies
| Autor: | Oleg Y. Gnedin, Edward W. Olszewski, Mario Mateo, Bodhisattva Sen, Matthew G. Walker, Xiao Wang, Michael Woodroofe |
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| Rok vydání: | 2007 |
| Předmět: |
Physics
Milky Way Astrophysics (astro-ph) Dark matter FOS: Physical sciences Velocity dispersion Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Radius Galaxy Stars Space and Planetary Science Satellite galaxy Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics Surface brightness Astrophysics::Galaxy Astrophysics |
| Zdroj: | The Astrophysical Journal. 667:L53-L56 |
| ISSN: | 1538-4357 0004-637X |
| DOI: | 10.1086/521998 |
| Popis: | We present stellar velocity dispersion profiles for seven Milky Way dwarf spheroidal (dSph) satellite galaxies. We have measured 8394 line-of-sight velocities (+/- 2.5 km/s) for 6804 stars from high-resolution spectra obtained at the Magellan and MMT telescopes. We combine these new data with previously published velocities to obtain the largest available kinematic samples, which include more than 5500 dSph members. All the measured dSphs have stellar velocity dispersion of order 10 km/s that remains approximately constant with distance from the dSph center, out to and in some cases beyond the radius at which the mean surface brightness falls to the background level. Assuming dSphs reside within dark matter halos characterized by the NFW density profile, we obtain reasonable fits to the empirical velocity dispersion profiles. These fits imply that, among the seven dSphs, M_vir ~ 10^[8-9] M_sun. The mass enclosed at a radius of 600 pc, the region common to all data sets, ranges from (2-7) x 10^7 M_sun . Accepted for publication in the Astrophysical Journal Letters |
| Databáze: | OpenAIRE |
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