Environmental Mechanisms Shaping the Nature of Dwarf Spheroidal Galaxies: The View of Computer Simulations
Figure 3
Evolution of structural parameters of a tidally stirred dwarf in a high resolution numerical simulation. The plot shows the results for one of the models studied by Klimentowski et al. [39], whose initial disk was oriented at 90 degrees with respect to the orbital plane (this is a conservative case since other orientations leave almost no residual angular momentum, see text in Section 3). Upper panel: the maximum circular velocity (solid line, left axis) and the radius at which the maximum circular velocity occurs (dashed line, right axis). Middle panel: the velocity dispersion (total 3D, and 1D along three different cylindrcal axes) expressed in units of the maximum circular velocity (indicated as in the text). Lower panel: evolution of the ratio of the mean rotation velocity to the total (3D) velocity dispersion and the angle between the total angular momentum vector of the stars and the orbital plane (dashed line, right axis). In all panels vertical dotted lines indicate pericentre passages. Loss of angular momentum due to tidally induced instabilities and simultaneous increase of stellar velocity dispersion owing to tidal heating lead to a low ratio comparable to that of dSphs. See Klimentowski et al. [39] for details on how internal angular momentum is lost.
