DESI Galaxy Flight
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Ahanu
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Today the DESI dark energy experiment reached the remarkable milestone of having successfully mapped all of the sky it originally planned to study, accomplishing the feat in less time than expected, while also mapping vastly more galaxies and stars than planned. Designed to measure, over a 5-year period, spectra of 34 million galaxies and quasars spread out over two-thirds of the northern sky, DESI has now successfully mapped more than 47 million galaxies and quasars, as well as 20 million stars in the Milky Way, over this area, completing the observations ahead of schedule.
The results have produced the largest high-resolution 3D map of the Universe ever made and raise new questions about the nature of dark energy and the expansion history of the Universe. Analyses of DESI’s first three years of data hint that dark energy, once thought to be a “cosmological constant”, may instead evolve over time, sparking great excitement in the cosmology community. The full survey dataset will allow these results to be measured with much greater precision. The collaboration will now begin processing the completed data, with the first dark energy results from DESI’s full five-year survey expected in 2027.
Building on this remarkable success, DESI is now set to continue mapping the sky through 2028, expanding its survey area by about 20%, from 14,000 square degrees to 17,000 square degrees and aiming to gather 63 million total extragalactic redshifts. The extended map will cover parts of the sky that are more challenging to observe: areas that are closer to the plane of the Milky Way and areas further south. The experiment will also revisit the current survey area to map out more distant and fainter “luminous red galaxies,” in order to produce a more detailed map that gives researchers a clearer picture of the Universe’s history. DESI will also study nearby dwarf galaxies and stellar streams in the Milky Way and the neighboring Andromeda galaxy to better understand dark matter, the invisible form of matter that accounts for most of the mass in the Universe but has never been directly detected.
The results have produced the largest high-resolution 3D map of the Universe ever made and raise new questions about the nature of dark energy and the expansion history of the Universe. Analyses of DESI’s first three years of data hint that dark energy, once thought to be a “cosmological constant”, may instead evolve over time, sparking great excitement in the cosmology community. The full survey dataset will allow these results to be measured with much greater precision. The collaboration will now begin processing the completed data, with the first dark energy results from DESI’s full five-year survey expected in 2027.
Building on this remarkable success, DESI is now set to continue mapping the sky through 2028, expanding its survey area by about 20%, from 14,000 square degrees to 17,000 square degrees and aiming to gather 63 million total extragalactic redshifts. The extended map will cover parts of the sky that are more challenging to observe: areas that are closer to the plane of the Milky Way and areas further south. The experiment will also revisit the current survey area to map out more distant and fainter “luminous red galaxies,” in order to produce a more detailed map that gives researchers a clearer picture of the Universe’s history. DESI will also study nearby dwarf galaxies and stellar streams in the Milky Way and the neighboring Andromeda galaxy to better understand dark matter, the invisible form of matter that accounts for most of the mass in the Universe but has never been directly detected.