Environmental Mechanisms Shaping the Nature of Dwarf Spheroidal Galaxies: The View of Computer Simulations
Figure 6
Evolution of the gas-dominated disky dwarf model studied in Mayer et al. [41], which produces a dark-matter-dominated dwarf resembling Draco after 10 Gyr of evolution. This N-Body + SPH simulation employed millions of dark matter, gas, and star particles. It included tidal mass loss due to a live Milky Way halo, ram-pressure stripping in a tenuous gaseous halo, radiative cooling, and a time-varying cosmic ionizing UV background consistent with the Haardt and Madau (2000) model. The snapshots show the color-coded logarithmic density maps (the brighter the color, the higher will be the density, with densities in the range g cm–3) for the first 2.5 Gyr of evolution. Boxes are 30 kpc on a side. The dwarf begins falling into the Milky Way halo on a typical eccentric cosmological orbit (apo/per at the beginning of the simulation, which corresponds to ). At the first pericenter passage ( kpc) a prominent ram-pressure tail is evident (top left), and once the dwarf comes to first apocenter (top right), it has lost already more than half of its gas. As it begins the second orbit, ram-pressure stripping continues to remove gas (bottom left), until all gas is stripped at second pericenter (bottom right).
