A Million Element Integral Field Unit (MEIFU)

We describe an instrument concept that will provide simultaneous spectra for a million spatial samples on the sky. With the proposed field of view and spectral resolution, it will be able to measure redshifts and line strengths for around 2-4000 z~3-7 galaxies in a 16 night campaign. The main science driver is to obtain a complete census of the star formation properties of galaxies with 2.5<z<6.7 as a function of luminosity, environment, morphology and redshift. This survey will also allow us to study the evolution of the 3 dimensional power spectrum and test the connection between these early galaxies and the large scale structure of the Lyman Alpha forest. Additional science drivers include [OII] emitters with 0.13<z<1.52, abundance gradients in nearby galaxies, searches for planetary nebulae in nearby galaxy groups and clusters, lensed emission line objects, and spectroscopic searches for objects with continuum breaks. We expect that this instrument will make an ideal partner to the HST ACS, where ACS morphology and broadband colour information can complement the MEIFU spectroscopy and help remove any degeneracies in line identification.