Topics on bar and bulge formation and evolution

TL;DR

This paper examines the evolution of barred and discy bulges in galaxies, showing a decline in bar fraction over time and simulating bulge formation through bar-driven radial inflow.

Contribution

It combines observational data from the COSMOS survey with N-body simulations to explain bar evolution and discy bulge formation in galaxies.

Findings

Bar fraction decreases from z ~ 0.2 to z ~ 0.8, especially in low-mass spirals.

Discy bulges are formed by bar-driven radial inflow, are disc-shaped, and contain young stars.

Simulations reproduce observed properties of discy bulges.

Abstract

I discuss results from the COSMOS survey, showing that the fraction of disc galaxies that is barred decreases considerably with look-back time from z ~ 0.2 to z ~ 0.8. This decrease is more important for small mass and low luminosity spirals. Classical bar formation theory provides a promising framework for understanding these results. I also discuss the formation of discy bulges using N-body simulations reproducing well the properties of observed discy bulges. Thus, these simulated discy bulges have the shape of a disc, they have Sersic profiles with small values of the shape index and their size is of the order of a kpc. They are formed by radial inflow of material driven by the bar and are thus composed of both gas and stars and have a considerable fraction of young stars. They can harbour spiral structure, or an inner bar.