The APOSTLE simulations: Rotation curves derived from synthetic 21-cm observations

The apostle cosmological hydrodynamical simulation suite is a collection of twelve regions ~5 Mpc in diameter, selected to resemble the Local Group of galaxies in terms of kinematics and environment, and re-simulated at high resolution (minimum gas particle mass of 10⁴ M_⊙) using the galaxy formation model and calibration developed for the eagle project. I select a sample of dwarf galaxies (60 < V_max/km s^-1 < 120) from these simulations and construct synthetic spatially- and spectrally-resolved observations of their 21-cm emission. Using the ^3Dbarolo tilted-ring modelling tool, I extract rotation curves from the synthetic data cubes. In many cases, non-circular motions present in the gas disc hinder the recovery of a rotation curve which accurately traces the underlying mass distribution; a large central deficit of dark matter, relative to the predictions of cold dark matter N-body simulations, may then be erroneously inferred.