GAMA. MegaMorp/GalfitM profile fits

Using simulated data, we find that multi-band fitting significantly reduces deviations from the real parameter values, allows component sizes and Sersic indices to be recovered more accurately, and - by design - constrains the band-to-band variations of these parameters to more physical values. On both simulated and real data, we confirm that the spectral energy distributions (SEDs) of the two main components can be recovered to fainter magnitudes compared to using single-band fitting, which tends to recover 'disks' and 'bulges' with - on average - identical SEDs when the galaxies become too faint, instead of the different SEDs they truly have.

By comparing our results to those provided by other fitting codes, we confirm that they agree in general, but measurement errors can be significantly reduced by using the multi-band tools developed by the MEGAMORPH project. We conclude that the multi-band fitting employed by Galapagos-2 and Galfitm significantly improves the accuracy of structural galaxy parameters and enables much larger samples to be be used in a scientific analysis.