We propose legacy survey observations of 42 of the most luminous northern luminous infra-red galaxies selected from the IRAS revised Bright Galaxy Sample (Sanders et al. 2003). This survey will provide a high spatial resolution radio complement to legacy observations made with the NASA Great Observatories (GOALS program). Additionally it will itself provide legacy data to be combined with upcoming radio/millimetre/submm instruments. Our sample selects sources with L= log(Lir/Lsol) >11.4, which have sizes well matched to eMERLIN spatial resolution. The sample spans the range of FIR luminosities from the upper end of the Luminous Infra-Red Galaxies (LIRGs) to Ultra- Luminous Infra-Red Galaxies (ULIRGs), most of which are merging or post merger systems. Our local (<260 Mpc) targets have properties of area star formation densities, gas and radiation densities similar to star-forming galaxies a high redshift. A major goal of future radio/millimetre instruments is to use these high redshift objects to trace the starformation (and galaxy assembly) history of the universe. Achieving this goal reliably requires understanding the physics of similar local objects. Crucially it is important to understand how accurately radio continuum flux densities can be converted to Star Formation Rates (SFR). If for instance in the warm dense gas environments of (U)LIRGs) the stellar Initial Mass Functions is top-heavy, the calibration of SFR from star-formation tracers can be affected. Definite evidence for non-standard IMFs in extreme environments would also be an important input into understanding star-formation mechanisms in general.

Original proposal (PDF)