Environmental Mechanisms Shaping the Nature of Dwarf Spheroidal Galaxies: The View of Computer Simulations
Figure 2
Top: color-coded logarithmic density maps of a tidally stirred dwarf seen face-on (i.e., with the line-of-sight perpendicular to the initial disk orientation, on the top) and edge-on (i.e., with the line-of-sight parallel to the initial disk orientation, on the bottom). The time increases from the left to right; each snapshot is separated by about half an orbital time (the orbital time is 2 Gyr in this simulation), starting with the time corresponding to the first pericenter passage, when the bar first appears. Boxes are 10 kpc on a side. The edge-on view shows clearly the buckling of the bar occurring on the second orbit, and the subsequent transformation into a diffuse spheroidal. Bottom: gray-scale surface brightness maps of the remnant of the simulation shown after 10 billion years of evolution (about 5 orbits). Two perpendicular viewing projections are shown. The limiting B band surface brightness shown in the images corresponds to mag and a B band stellar mass-to-light ratio of 5 was adopted for converting surface mass density into surface brightness (see [14] on models for the evolution of the luminosity and stellar mass-to-light ratio in the tidally stirred dwarf). The faint simulated remnant resembles classic dSphs such as Draco or Carina in both apparent shape and luminosity and surface brightness distribution.
