Successful Start of Dark Energy Spectroscopic Instrument, Its ‘Eyes’ Designed by U-M Physicist Gregory Tarlé and Research Team
The Dark Energy Spectroscopic Instrument, or DESI, is an international collaboration under the aegis of the Department of Energy’s Lawrence Berkeley National Laboratory with primary funding from DOE’s Office of Science. The project aims to create a 3D map of the universe, unraveling the mysterious dark energy. To complete its quest, the instrument will capture and study the light from tens of millions of galaxies and other distant objects in the universe.
To do this, the instrument will aim its robotic array of 5,000 fiber-optic “eyes” at the night sky to capture the first images showing its unique view of galaxy light. The robotic eyes were assembled by U-M students and technicians, under the leadership of physicist Gregory Tarlé. The team delivered a total of 7,300 robotic fiber positioners, including spares.
By gathering light from some 30 million galaxies, project scientists say DESI will help them construct a 3D map of the universe with unprecedented detail. The data will help them better understand the repulsive force associated with dark energy that drives the acceleration of the expansion of the universe across vast cosmic distances.
What sets DESI apart from previous sky surveys?
“DESI is the most advanced cosmic cartography experiment ever attempted. By observing the spectrum of tens of millions of galaxies and quasars, ten times more than any previous experiment, DESI will construct a detailed three-dimensional map of our universe,” said Tarlé, U-M professor of physics and chair of the DESI Institutional Board.
“With this map, we will be able to trace the impact of the mysterious dark energy through 11 billion years of cosmic time and attempt to understand its nature. This is such an exciting time, marking the culmination of almost a decade of work by dozens of institutions from all over the world to build DESI, carry out the targeting surveys and make it work on the sky.”
DESI’s components are designed to automatically point at preselected sets of galaxies, gather their light and then split that light into narrow bands of color to precisely map their distance from Earth and gauge how much the universe expanded as this light traveled to Earth. In ideal conditions, DESI can cycle through a new set of 5,000 galaxies every 20 minutes.
“We will measure 10 times more galaxy spectra than ever obtained. These spectra get us a third dimension,” said project director Michael Levi of the Berkeley Lab.
Instead of two-dimensional images of galaxies, quasars and other distant objects, he explained, the instrument collects light, or spectra, from the cosmos such that it “becomes a time machine where we place those objects on a timeline that reaches as far back as 11 billion years ago.”
The formal start of DESI’s five-year survey follows a four-month trial run of its custom instrumentation that captured spectra from four million galaxies—more than the combined output of all previous spectroscopic surveys.
The DESI instrument resides at the retrofitted Mayall Telescope at the National Science Foundation’s Kitt Peak National Observatory in Arizona.
To read more, please click on the news release from Morgan Sherburne, Senior Public Relations Representative, U-M News.
DES Video: Learn more about DESI’s quest and how its designers look to unravel the mysteries of dark energy.