The Dark Energy Spectroscopic Instrument (DESI), currently pointing toward the sky from its home in the Nicholas U. Mayall Telescope at the Kitt Peak National Observatory in Arizona, is tasked with mapping the expansion of space, examining dark energy and creating the most detailed 3D map of the universe that has ever been put together.
Only seven months have passed since DESI’s mission, and we already have a record-breaking, jaw-dropping, three-dimensional image of the galaxy around us, proving DESI’s capabilities and the potential it has to map space.
DESI has already cataloged and mapped more than 7.5 million galaxies, with more than one million new ones being added per month. By the time the scan completes in 2026, it is estimated that over 35 million galaxies will have been mapped, giving astronomers a huge data library to mine.
“There’s a lot of beauty in it,” says astrophysicist Julien Guy of the Lawrence Berkeley National Laboratory in California.
“In the distribution of the galaxies on the 3D map, there are huge clusters, filaments and cavities. They are the largest structures in the universe. But in them you will find an imprint of the very early universe and the history of the universe. Its expansion since then. “
DESI consists of 5,000 optical fibers, each individually controlled and placed by its own little robot. These fibers must be placed exactly within 10 microns or less than the thickness of a human hair, and they then capture flashes of light as they filter down to Earth from the cosmos.
Through this fiber network, the instrument takes color spectrum images of millions of galaxies covering more than a third of the entire sky before calculating how much light has been redshifted – that is, how much it has been pushed towards the red end of the spectrum due to the expansion of the universe.
Since this light can take up to billions of years to reach Earth, it is possible to use redshift data to see the depth of the universe: The greater the redshift, the farther away something is. In addition, the structures mapped by DESI can be conversely constructed to see the initial formation in which they started.
Over: A snippet of the 3D map of galaxies from the completed Sloan Digital Sky Survey (left) and the first few months of the Dark Energy Spectroscopic Instrument (right).
The main purpose of DESI is to reveal more about the dark energy that is thought to make up 70 percent of the universe, as well as to accelerate its expansion. This dark energy can propel galaxies into infinite expansion, cause them to collapse back on themselves or something in between – and cosmologists are eager to narrow down the possibilities.
“[DESI] will help us search for clues about the nature of dark energy, “Carlos Frenk, a cosmologist from Durham University in the UK, told the BBC.
“We will also learn more about the dark matter and the role it plays in how galaxies like the Milky Way are formed and how the universe evolves.”
The 3D map, which has already been released, shows that scientists do not have to wait for DESI to complete its work to start taking advantage of its deep look into space. Other DESI-enhanced research examines whether smaller galaxies have their own black holes, just as larger galaxies have.
The best way to spot a black hole is to identify the gas, dust, and other material that is drawn into it, but it is not easy to see in smaller galaxies – something that the high-precision spectral data collected by DESI should help with.
Then there is the study of quasars, especially bright galaxies driven by supermassive black holes, which serve as guides back through billions of years of space history. DESI will be used to test a hypothesis about quasars: that they start surrounded by a mantle of dust that is driven off as time goes on.
The amount of dust around a quasar is thought to affect the color of the light it emits, making it a perfect job for DESI. The instrument should be able to collect information on about 2.4 million quasars when the study is completed.
“DESI is really amazing because it picks up much weaker and much redder objects,” says astronomer Victoria Fawcett from Durham University.
“We find quite a few exotic systems, including large samples of rare objects, that we just have not been able to study in detail before.”
You can follow the latest news from the Dark Energy Spectroscopic Instrument on its official website.