The Dark Energy Spectroscopic Instrument (DESI) is a ground-based dark energy experiment that will study baryon acoustic oscillations and the growth of structure through redshift-space distortions with a wide-area galaxy and quasar redshift survey. For that purpose the project is building a multifiber spectrograph with the goal to obtain tens of millions of spectra to map the structure of the universe and study dark energy. DESI observations will probe diverse aspects of cosmology, from dark energy to alternatives to General Relativity to neutrino masses to the early Universe. The data from DESI will be used to create three-dimensional maps of the distribution of matter covering a very large volume of the Universe in great detail. DESI will measure the expansion history of the Universe using the baryon acoustic oscillations (BAO) imprinted in the clustering of galaxies, quasars, and the intergalactic medium.

Mayall Telescope at Kitt Peak (Arizona, USA). Credit: DESI

The DESI instrument is a robotically-actuated, fiber-fed spectrograph capable of taking up to 5,000 simultaneous spectra over a wavelength range from 360 nm to 980 nm. This powerful instrument will be installed at prime focus on the 4-m Mayall telescope in Kitt Peak, Arizona, along with a new optical corrector, which will provide a three-degree diameter field of view. The DESI instrument will be used to conduct a five-year survey designed to cover 14,000 square degrees. To trace the underlying dark matter distribution, spectroscopic targets will be selected in four classes from imaging data: 1) Luminous red galaxies up to redshift 1.0; 2) Bright [O II] emission line galaxies up redshift 1.7; 3) Quasars will be used as direct tracers of the underlying dark matter distribution and for the Ly-alpha forest absorption features; and 4) a 10-million sample of bright galaxies. In total, over 30 million galaxy and quasar redshifts will be obtained to measure the BAO feature and determine the matter power spectrum, including redshift space distortions.

The IEEC, through the Institute of Space Sciences (ICE, CSIC), participates in the DESI project as part of the BCN-MAD Regional Participation Group (RPG), composed of IEEC-CSIC, IFAE, CIEMAT and IFT. We represent our RGP in the DESI Institutional Board. Our RPG is responsible for delivering the Guiding, Focus and Alignment units of DESI's focal plane. We are also responsible of delivering the guiding software for the instrument. We lead the Image Validation Working Group and participate in other Working Groups

More information:

DESI website

Generalitat de CatalunyaUniversitat de BarcelonaUniversitat Autònoma de BarcelonaUniversitat Politècnica de CatalunyaConsejo Superior de Investigaciones CientíficasCentres de Recerca de Catalunya