|A ‘computed tomography’ of the Universe across more than 5 billion light-years. (D. Schlegel/Berkeley Lab/DESI DATA|
The Dark Energy Spectroscopic Instrument (DESI), currently pointing skyward from its home on the Nicholas U. Mayall Telescope at Kitt Peak National Observatory in Arizona, is tasked with tracking the expansion of space, studying dark energy, and creating the most detailed 3D. Map. of the Universe that was never assembled.
It’s only been seven months since the DESI mission began, and we already have a stunning, record-breaking three-dimensional image of the galaxy around us, demonstrating DESI’s capabilities and potential for mapping space.
DESI has already cataloged and tracked more than 7.5 million galaxies, with more than a million new additions per month. When the scan is fully completed in 2026, more than 35 million galaxies will have been mapped, giving astronomers a huge library of data to mine.
“There’s a lot of beauty there,” says Lawrence astrophysicist Julien Guy in California. “In the distribution of galaxies on the 3D map, there are huge clusters, filaments and voids. These are the largest structures in the Universe.
But within them you will find a trace of the early Universe and the history of its expansion, as DESI is made up of 5,000 optical fibers, each individually controlled and positioned ionized by its own little robot. These fibers must be precisely placed within 10 microns, less. than the thickness of a human hair, and then catch glimpses of light as they filter through the Earth of the cosmos.
Through this fiber network, the instrument takes images of the color spectrum of millions of galaxies, covering more than a third of the entire sky, before calculating how much light has been red shifted – that is, how much has been pushed towards the red end of the spectrum due to the expansion of the Universe.
As this light can take several billion years to reach Earth, it is possible to use redshift data to see the depth of the Universe: the greater the redshift, the further away something is. Additionally, DESI-mapped structures can be reverse-engineered to see the initial formation in which they started.
DESI’s main goal is to reveal more about the dark energy that is thought to make up 70 percent of the Universe, as well as speed up its expansion. This dark energy could drive galaxies into infinite expansion, collapse in on themselves, or something in between, and cosmologists are eager to narrow down the options.
[DESI] It will help us search for clues about the nature of dark energy”, Carlos Frenk, cosmologist at the University of Durham in the United Kingdom, told the bbc. We will also learn more about dark matter and the role it plays in how it happens, forms galaxies like the Milky Way, and how the universe evolves.
The 3D map that has already been released shows that scientists don’t have to wait for DESI to finish its work to start benefiting from its deep-space look exploring whether or not small galaxies have their own black holes like large galaxies.
The best way to detect a black hole is to identify the gas, dust and other material drawn into it, but that’s not easy to see in small galaxies, something where the high-precision spectral data collected by DESI should help. Then there is the study of quasars
, particularly bright galaxies powered by supermassive black holes, serving as clues to billions of years of space history.
DESI will be used to test a hypothesis about quasars: that they start out surrounded by an envelope of dust that dissipates over time. 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 tool should be able to collect information on about 2.4 million quasars before its study is complete. “DESI is really cool because it collects much fainter and much redder objects,” says Durham University astronomer Victoria Fawcett.
“We’re finding quite a few exotic systems, including large samples of rare objects that we’ve simply never seen before capable of studying in detail.
Fountain: science alert