Abstract:
In this study, we investigated the role of the inner halo's angular momentum distribution on bar formation and evolution processes. We performed a series of high-resolution N-body experiments with Milky Way-type disk galaxies. These models were initiated with similar disks but with varying inner halo angular momentum in the surrounding dark matter halo. The bar triggered earlier in the model with higher inner halo angular momentum compared to models with lower values, consistent with studies suggesting the importance of halo spin. However, the bar's secular evolution showed growth in all models, regardless of inner halo angular momentum, contradicting the notion that high spin suppresses bar growth as suggested in earlier studies. The model with the highest inner angular momentum displayed a more pronounced box/peanut/x-shaped bulge compared to the one with the lowest. Our results on the role of halo angular momentum discontinuity revealed that the bar's secular growth followed the models with continuous halo angular momentum distribution. In contrast, the bar's growth was suppressed in models with a discontinuous distribution. These studies provide valuable insights into the complex processes of bar formation. Finally, using multiple approaches, including linear perturbation theory, test particle simulations, and N-body simulations, we demonstrated that dynamical friction exerted by dark matter on the bar weakens with increasing net prograde rotation of the dark matter halos.
