On the Origin of Exponential Galaxy Disks

Understand

We use a disk galaxy evolution model to investigate whether galaxies with exponential surface brightness profiles can be produced in a cosmologically motivated framework for disk galaxy formation.

• Our model follows the accretion, cooling, and ejection of baryonic mass, as a function of radius, inside growing dark matter haloes.
• The surface density profile of the disk is determined by detailed angular momentum conservation, starting from the distribution of specific angular momentum as found in cosmological simulations.
• Exponential and quasi-exponential disks can be produced by our model through a combination of supernova driven galactic outflows (which preferentially remove low angular momentum material), intrinsic variation in the angular momentum distribution of the halo gas, and the inefficiency of star formation at large radii.