3D barolo: a new 3D algorithm to derive rotation curves of galaxies

We present |$^{3small {D}}$|barolo,† a new code that derives rotation curves of galaxies from emission-line observations. This software fits 3D tilted-ring models to spectroscopic data cubes and can be used with a variety of observations: from H i and molecular lines to optical/IR recombination lines. We describe the structure of the main algorithm and show that it performs much better than the standard 2D approach on velocity fields. A number of successful applications, from high to very low spatial resolution data are presented and discussed. |$^{3small {D}}$|barolo can recover the true rotation curve and estimate the intrinsic velocity dispersion even in barely resolved galaxies (∼2 resolution elements) provided that the signal to noise of the data is larger than 2–3. It can also be run automatically thanks to its source-detection and first-estimate modules, which make it suitable for the analysis of large 3D data sets. These features make |$^{3small {D}}$|barolo a uniquely useful tool to derive reliable kinematics for both local and high-redshift galaxies from a variety of different instruments including the new generation Integral Field Units, ALMA and the SKA pathfinders.