The assembly of galaxies can be described by the distribution of their star formation as a function of cosmic time .
Thanks to the WFC3 grism on HST it is now possible to measure this beyond the local Universe .
Here we present the spatial distribution of H \alpha emission for a sample of 54 strongly star-forming galaxies at z \sim 1 in the 3D-HST Treasury survey .
By stacking the H \alpha emission we find that star formation occurred in approximately exponential distributions at z \sim 1 , with median Sérsic index of n = 1.0 \pm 0.2 .
The stacks are elongated with median axis ratios of b / a = 0.58 \pm 0.09 in H \alpha consistent with ( possibly thick ) disks at random orientation angles .
Keck spectra obtained for a subset of eight of the galaxies show clear evidence for rotation , with inclination corrected velocities of 90 to 330 km/s .
The most straightforward interpretation of our results is that star formation in strongly star-forming galaxies at z \sim 1 generally occurred in disks .
The disks appear to be `` scaled-up '' versions of nearby spiral galaxies : they have EW ( H \alpha ) \sim 100Å out to the solar orbit and they have star formation surface densities above the threshold for driving galactic scale winds .