First batch of DESI data available for scientists to mine

Early Dark Energy Spectroscopic Instrument (DESI) release holds nearly two million objects, including distant galaxies, quasars and stars in our own Milky Way.
Shubhangi Dua
The Dark Energy Spectroscopic Instrument sits atop the Mayall 4-Meter Telescope at Kitt Peak National Observatory. DESI’s early data gathered in 2020 and 2021 is now publicly available
The Dark Energy Spectroscopic Instrument sits atop the Mayall 4-Meter Telescope at Kitt Peak National Observatory. DESI’s early data gathered in 2020 and 2021 is now publicly available

Marilyn Sargent/Berkeley Lab 

Dark Energy Spectroscopic Instrument (DESI), the most robust multi-object survey spectrograph, capable of mapping more than 40 million galaxies, quasars, and stars, recorded an 80-terabyte data set this Tuesday. 

The data was collected after 2,480 exposures taken over six months during the experiment’s “survey validation” phase in 2020 and 2021, said Lawrence Berkeley National Lab.  

The study is being conducted in collaboration with the Department of Energy Office of Science with the instrument aiming to undertake the Stage IV dark energy measurement.

The process requires the use of baryon acoustic oscillations and other techniques that depend on spectroscopic measurements.

DESI co-spokesperson and scientist at Berkeley Lab (also managing the experiment), Nathalie Palanque-Delabrouille said:

“This milestone shows that DESI is a unique spectroscopic factory whose data will not only allow the study of dark energy but will also be coveted by the whole scientific community to address other topics, such as dark matter, gravitational lensing, and galactic morphology.”

Featuring DESI

According to the Berkeley Lab, the telescope uses 5,000 robotic positioners to move optical fibers that capture light from objects millions or billions of light-years away.

DESI has the application to measure light from more than 100,000 galaxies in one night alone.

The instrument is equipped to build a 3D cosmic map using the light interface even if the object is far. 

Researchers were able to capture detailed images across 20 different directions in the sky under the spectrograph’s recent survey validation conducted by the “One-Percent Survey.”

DESI created a three-dimensional map estimating 700,000 objects which represents just one percent of the total volume DESI is designed to analyze. 

Previous data from the spectrograph released in April this year shed light on the instrument’s initial measurement of the cosmological distance scale. The new data expanded the research, filled in the gaps, and confirmed DESI’s potential.

Study findings

“This measurement utilized the first two months of regular survey data, not included in the early data release. It demonstrated that DESI successfully achieved its intended objectives,” the press release states. 

The data allowed scientists to find some intriguing evidence of a mass migration of stars into the Andromeda galaxy, and incredibly distant quasars, the extremely bright and active supermassive black holes sometimes found at the center of galaxies.

Anthony Kremin, a PhD researcher at Berkeley Lab who led the data processing for the early data release says, “We observed some areas at very high depth. People have looked at that data and discovered very high redshift quasars, which are still so rare that basically, any discovery of them is useful.” 

Kremin adds that the high-redshift quasars are usually found with very large telescopes. Therefore, it’s a huge achievement because it implies that DESI – a smaller, 4-meter survey instrument – could compete with those larger, dedicated observatories. 

By obtaining the optical spectra for tens of millions of galaxies and quasars, DESI will construct a comprehensive 3D map covering a remarkable distance, ranging from the nearby universe to a staggering 11 billion light-years away.

The spectroscopic instrument will continue to study the impact of dark energy on cosmic expansion

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