Program: GN-2010A-Q-28

Herschel has now successfully launched, and commenced routine operations. The multiple far-IR bands of Herschel, coupled with its ability to deeply survey large areas of sky on rapid timescales, makes it the ideal instrument to resolve some of the key problems in galaxy formation raised by instruments such as SCUBA. In this proposal we aim to take the first steps in exploiting the enormous power of Herschel, by using GMOS to obtain redshifts and spectral diagnostics for some of the most extreme objects that Herschel detects in the HerMES guaranteed time survey. These are rare (1 per square degree) sub-mm bright, optically faint sources at 0.5<z<1, expected to be objects with star-formation rates exceeding 1000Msun/yr - likely massive systems undergoing their last major star formation episode. Herschel is the first observatory that can easily identify such systems and produce statistically significant samples of them. This proposal represents an opportunity for Gemini to take an early lead in the exploration of the new parameter space opened up by Herschel.