HST/WFC3 observations in HUDF and GOODS-S

The WFC3 NIR images reveal galaxies at these redshifts that were undetected in the rest-frame UV HUDF/GOODS images, as well as true centers and regular disks in galaxies classified as highly irregular in rest-frame UV light.

Across the 1.5<z<2.15 redshift range, regular disks are unveiled in the WFC3 images of ~25% of both intermediate and high mass galaxies, i.e., above 10^10^M_{sun}_. Meanwhile, galaxies maintaining diffuse and/or irregular morphologies in the rest-frame optical light - i.e., not yet dynamically settled - at these epochs are almost entirely restricted to masses below 10^11^M_{sun}_. In contrast at 2.25<z<3.5 these diffuse and/or irregular structures overwhelmingly dominate the morphological mix in both the intermediate and high mass regimes, while no regular disks, and only a small fraction (~25%) of smooth spheroids, are evident above 10^11^M_{sun}_.