Dynamical Properties of z~2 Star Forming Galaxies and a Universal Star Formation Relation

We present the first comparison of the dynamical properties of different samples of z~1.4-3.4 star forming galaxies from spatially resolved imaging spectroscopy from SINFONI/VLT integral field spectroscopy and IRAM CO millimeter interferometry. Our samples include 16 rest-frame UV-selected, 16 rest-frame optically-selected and 13 submillimeter galaxies (SMGs). We find that restframe UVand optically bright (K ranging from 0.06 to 0.2. In contrast bright SMGs (S850μm≥5 mJy) have larger velocity widths and are much more compact. Hence, SMGs have lower angular momenta and higher matter densities than either of the UVor optically selected populations. This indicates that dissipative major mergers may dominate the SMGs population, resulting in early spheroids, and that a significant fraction of the UV/optically bright galaxies have evolved less violently, either in a series of minor mergers, or in rapid dissipative collapse from the halo, given that either process may leads to the formation of early disks. These early disks may later evolve into spheroids via disk instabilities or mergers. Because of their small sizes and large densities, SMGs lie at the high surface density end of a universal (out to z=2.5) ‘Schmidt-Kennicutt’ relation between gas surface density and star formation rate surface density. The best fit relation suggests that the star formation rate per unit area scales as surface gas density to power ~1.7, and that the star formation efficiency increases by a factor 4 between non-starbursts and strong starbursts.