The map covers more than 14,000 square degrees of sky – nearly one-third of the entire night sky. DESI allows researchers to map objects up to 11 billion light-years away.
DESI can observe patterns in the cosmos called baryonic acoustic oscillations (BAOs) whcih were created after the Big Bang, when the universe was filled with a hot plasma of atomic nuclei and electrons.
Density waves associated with quantum fluctuations in the Big Bang rippled through this plasma, until about 379,000 years after the Big Bang. Then, the temperature dropped sufficiently to allow the atomic nuclei to sweep up all the electrons.
This froze the plasma density waves into regions of high mass density (where galaxies formed) and low density (intergalactic space). These density fluctuations are the BAOs; and they can be mapped by doing statistical analyses of the separation between pairs of galaxies and quasars.
Long exposure star trails over the Mayall telescope where DESI is installed.
(Credit: Luke Tyas, Berkeley Lab and KPNO/NOIR Lab/NSF/AURA).
