Bulge formation through disc instability
T. Devergne, A. Cattaneo, F. Bournaud, I. Koutsouridou, A. Winter, P. Dimauro, G. A. Mamon, W. Vacher, M. Varin
Abstract
We use simulations to study the growth of a pseudobulge in an isolated thin exponential stellar disc embedded in a static spherical halo. We observe a transition from later to earlier morphological types and an increase in bar prominence for higher disc-to-halo mass ratios, for lower disc-to-halo size ratios, and for lower halo concentrations. We compute bulge-to-total stellar mass ratios B / T by fitting a two-component Sérsic-exponential surface-density distribution. The final B / T is strongly related to the disc’s fractional contribution f d to the total gravitational acceleration at the optical radius. The formula B / T = 0.5 f d 1.8 fits the simulations to an accuracy of 30%, is consistent with observational measurements of B / T and f d as a function of luminosity, and reproduces the observed relation between B / T and stellar mass when incorporated into the G AL ICS 2.0 semi-analytic model of galaxy formation.