Rest-frame optical spectroscopy provides basic insight into the stellar and gaseous contents of galaxies. Until recently, our knowledge of the rest-frame optical spectroscopic properties of galaxies at z > 1.5 has been extremely limited, despite the critical importance of this cosmic epoch for the assembly of galaxies and the growth of black holes. The recent commissioning of the MOSFIRE spectrograph on the Keck I telescope represents a major development for the study of the rest-frame optical properties of high-redshift galaxies, given the significant increase in sensitivity (~5) and survey efficiency (>100).
The MOSFIRE Deep Evolution Field (MOSDEF) Survey fully exploits the new capabilities of MOSFIRE, charting the evolution of the rest-frame optical spectra for ~1500 galaxies in three distinct redshift intervals spanning 1.4 < z < 3.8 more than an order of magnitude improvement over existing surveys. The MOSDEF team has been awarded 44 nights of MOSFIRE observing time by the University of California Keck Time Allocation Committee. This observing time spans four years during the period 2013 through 2016, in addition to an initial allocation of 3 nights during December 2012. The MOSDEF survey is being conducted in three extragalactic survey fields (AEGIS, COSMOS, and GOODS-N) with extensive multi-wavelength datasets spanning from the radio to X-ray regimes. The existing multi-wavelength data enable robust targeting of high-redshift galaxies for MOSFIRE spectroscopy, and in turn provide a comprehensive perspective of their broad spectral energy distributions and structural properties. Combining new MOSFIRE spectra with existing multi-wavelength data, the MOSDEF team will characterize the star-formation and AGN activity in distant galaxies, their masses, contents and structures, and the manner in which baryonic matter passes through them. In collaboration with a team of theorists studying galaxy formation, star formation, and baryon cycling, the MOSDEF team will use these new observational results to test and inform forefront models of galaxy evolution.