ABSTRACT:
As the largest gravitationally-bound structures in the Universe, galaxy clusters are efficient gravitational lenses, magnifying the images of distant galaxies that lie behind them by factors of up to 100x. This magnification allows us to study "typical" high-redshift galaxies in a level of detail that would otherwise have to wait until JWST or the next generation of ground-based telescopes. I will present the results of two programs to map the star formation in gravitationally lensed galaxies at 1 < z < 5: one with narrowband imaging from HST/WFC3 and an integral field spectroscopy program with VLT/SINFONI, Keck/OSIRIS and Gemini/NIFS. With these data, I will show that the "clumpy" morphologies observed in high-redshift star-forming galaxies are a natural consequence of the rapidly evolving gas mass fraction and dynamics of turbulent disks.