Velocity Dispersion Profiles of Seven Dwarf Spheroidal Galaxies - AstrophysicsReportar como inadecuado

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Abstract: We present stellar velocity dispersion profiles for seven Milky Way dwarfspheroidal dSph satellite galaxies. We have measured 8394 line-of-sightvelocities +- 2.5 km-s for 6804 stars from high-resolution spectra obtainedat the Magellan and MMT telescopes. We combine these new data with previouslypublished velocities to obtain the largest available kinematic samples, whichinclude more than 5500 dSph members. All the measured dSphs have stellarvelocity dispersion of order 10 km-s that remains approximately constant withdistance from the dSph center, out to and in some cases beyond the radius atwhich the mean surface brightness falls to the background level. Assuming dSphsreside within dark matter halos characterized by the NFW density profile, weobtain reasonable fits to the empirical velocity dispersion profiles. Thesefits imply that, among the seven dSphs, M vir ~ 10^8-9 M sun. The massenclosed at a radius of 600 pc, the region common to all data sets, ranges from2-7 x 10^7 M sun .

Autor: Matthew G. Walker, Mario Mateo, Edward W. Olszewski, Oleg Y. Gnedin, Xiao Wang, Bodhisattva Sen, Michael Woodroofe


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