Gigamasers: the key to the dust-obscured star-formation history of the Universe?

We discuss the possibility of using OH and H2O gigamasers to trace the redshift distribution of luminous, dust-obscured, star-forming galaxies. It has long been thought that ultraluminous, interacting galaxies should host gigamasers due to their vast pumping infrared (IR) luminosity, the large column density of molecules available to populate the maser states and the turbulent motion of the gas in these dynamically complex systems which allows unsaturated maser emission. OH masers may thus be well-suited to the redshift-blind detection of ultraluminous and hyperluminous infrared galaxies (LFIR � 10 12 L⊙) such as those uncovered by the SCUBA submillimetre camera. The bandwidth requirement is low, < 1 GHz for z = 1–10 (lower still if additional redshift constraints are available) and the dual-line 1665-/1667-MHz OH spectral signature can act as a check on the reality of detections.