THE BAR INSTABILITY REVISITED IN COSMOLOGICAL SCENARIO

About two-thirds of spiral galaxies are classified as barred: only one-third is very strongly barred (SB) and the other is classified as "intermediate" SB galaxies, i.e. galaxies with a faint bar. Bars are quasi-stationary density waves originated by swing amplification mechanisms. We use smooth-particle-hydrodynamical simulations to give insights into the role triaxiality of the halo on triggering the bar instability and to investigate how tidal interactions act on the bar evolution. We argue that the triaxiality of the primordial halo and the weight of the halo have a fundamental role in monitoring the incidence of the bar instability in spiral galaxies.