| Project Detail |
Tracing the assembly history of galaxies over cosmic time is a foremost goal in the exploration of the Universe. Surveys have long shown that galaxies are predominantly either actively forming stars or in a so-called quenched state of almost no star formation. However, despite the remarkable evidence for the sharp build-up of this quiescent population at z<2 (~ 3.5 Gyr after the Big Bang), the underlying processes(s) and the conditions that trigger them still form an unsolved puzzle and a major open question for the formation and evolution of galaxies. There is no shortage of proposed physical mechanisms but the observational evidence, that will distinguish between their relative importance and sphere of influence, is not decisive yet. One limitation is the lack of sufficient redshift baseline to test evolution with lookback time. The current optical spectrographs can not reach beyond z>1; a wide-area, deep spectroscopic survey at near-IR wavelengths is required.To this end, this project builds on the advent of a new wide-field near-IR spectrograph, MOONS, to be mounted on the Very Large Telescope (VLT) of the European Southern Observatory (ESO). MOONS is a major project of Swiss national interest. A total of 190 nights of guaranteed time observations (GTO) will be dedicated to extragalactic science. They will fill in a critical gap, unveiling the so-called redshift desert at 1.5
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