The Rotation Curve of Simulated and Real Galaxies

Abstract
We discuss the accuracy for the recovery of mass profiles in simulated dwarf galaxies. We also present cosmologically motivated, high resolution N-body models for two nearby dwarf galaxies: NGC 3109 and NGC 6822. The rotation curves in our models are measured using standard observational techniques, projecting velocities along the line of sight of an artificial observer and performing a tilted ring analysis. Our models reproduce the rotation curves of both galaxies, the disk surface brightness profiles as well as the profile of isophotal ellipticity and position angle. We show that non-circular motions combined with gas pressure support and projection effects systematically underestimate by up to 50% the rotation velocity of cold gas in the central 1 kpc region, creating the illusion of a constant density core.