2006ApJ...640..228T

We present ∼0".6 resolution IRAM PdBI interferometry of eight submillimeter galaxies at z∼2-3.4, where we detect continuum at 1 mm and/or CO lines at 3 and 1 mm. The CO 3-2/4-3 line profiles in five of the sources are double-peaked, indicative of orbital motion either in a single rotating disk or of a merger of two galaxies. The millimeter line and continuum emission is compact; we marginally resolve the sources or obtain tight upper limits to their intrinsic sizes in all cases. The median FWHM diameter for these sources and the previously resolved sources, SMM J023952-0136 and SMM J140104+0252, is ≤0".5 (4 kpc). The compactness of the sources does not support a scenario in which the far-IR/submillimeter emission comes from a cold (T<30 K), very extended dust distribution. These measurements clearly show that the submillimeter galaxies (SMGs) we have observed resemble scaled-up and more gas-rich versions of the local universe, ultraluminous galaxy population. Their central densities and potential well depths are much greater than those in other z∼2-3 galaxy samples studied so far. They are comparable to those of elliptical galaxies or massive bulges. The SMG properties fulfill the criteria of ``maximal'' starbursts, in which most of the available initial gas reservoir of 10¹⁰-10¹¹ M_☉ is converted to stars on a timescale ∼3-10t_dyn∼a few times 10⁸ yr.