On the ratio between the halo and disk masses in the Galaxy

The evolution and final stationary states of model galaxies consisting of a halo with a density of rho(r) approximately r-2 and rho(r) approximately r-4 and a disk of a finite thickness with N=200 particle-stars with an exponential surface density are investigated by numerical experiments. The instability of the bar mode is supressed when the ratio of the masses of the halo and disk Msub(H)/Msub(D)> or approximately 1. As far as this instability is concerned, the best stabilizing properties are possessed by the haloes most concentrated toward the center (rho approximately r-4 with a small size of the nucleus). With respect to the ratio of the radial velocity dispersion csub(r) to the circular velocity V, experiments agree with observational data in the Sun's vicinity at Msub(H)/Msub(D) approximately equal to 2 (within the sphere r<=10 kpc). The local stability criterion is obtained which takes into account both the smaller stability of nonaxisymmetrical perturbations in comparison with the axisymmetrical ones and the local characteristics of the disk parameter inhomogeneities. Comparison between the critical velocity dispersion in this criterion with the experimental one, csub(r), shows that the disk, as a result of the evolution, arrives at a state close to the stability boundary. In the region studied, Msub(H)/Msub(D)<=3, instability of bending oscillations of the disk is not detected