The DESI Project

The Dark Energy Spectroscopic Instrument (DESI) will measure the effect of the dark energy in the expansion rate of the Universe with unprecedented precision. The Baryon Acoustic Oscillations (BAO) distance scale and its evolution with the redshift will be used as the main probe. The BAO scale is a well know technique nowdays, but DESI will drive it to its maxuimum precision level. DESI will also measure the growth of structure of the Universe through the Redshift Space Distortions (RSD) in the galaxy distribution. These measurement will allow a test of the current gravity theory, the General Relativity, at cosmological scales.

In order to perform these emasurements, DESi will observe the spectra of tens of millions galaxies, and will buuild a 3D map spanding from the nearby universe to distances of the order of 10 billion lightyears.The precision of the measurements and the huge map will allow DESi to measure the sum of neutrino masses with precision of ~20 meV. Such precise determination ensures the first direct detection of neutrino mases with significance larger than 3σ and the exclusion of the inverse hierarchy at more than 99% C. L. if the hierarchy is normal, even if the masses are minimal.

DESI is being built and installed at the 4m Mayall telescope, in the Kitt Peak observatory, and will start observing in 2019, becoming the first Stage 4 (in the DTEF classification) project that will take data.