An international team of scientists including astrophysicists and cosmologists at Durham University has helped to create the most detailed 3-D map of the universe ever.
The Dark Energy Spectroscopic Instrument (DESI) has capped off the first seven months of its survey run by smashing through all previous records for three-dimensional galaxy surveys.
DESI is an international science collaboration managed by the United States’ Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) with primary funding for construction and operations from the DOE’s Office of Science. Durham is a key partner of DESI and helped design and build the new telescope instrument.
Scientists are presenting DESI’s performance, and some early astrophysics results, on Thursday 13 January during a webinar called CosmoPalooza, hosted by Berkeley Lab, USA, which will also feature updates from other leading cosmology experiments.
Although it is already producing unprecedented outcomes, DESI is only about ten per cent through its five-year mission.
Once completed, its phenomenally detailed 3-D map will give scientists a better understanding of dark energy – the mysterious substance that accounts for 70 per cent of the content in the universe and is speeding up its expansion.
This will further our understanding of the past—and future—of the cosmos, helping scientists determine if the universe will expand forever, collapse in on itself in a reverse Big Bang or rip itself apart.
DESI features new optics that increase the field of view of the telescope and includes 5,000 robotically controlled optical fibres.
Led by Durham, the fibre-optic system will split light from objects in space such as galaxies, quasars and stars into narrow bands of colour and reveal the chemical make-up of objects as well as information about how far away they are and how fast they are travelling.
By looking at how far and how quickly galaxies and quasars are moving away from Earth, researchers will be able to gauge how much and how fast the universe has been expanding.
The 3D map will show a detailed distribution of galaxies which is expected to give new insights on the influence and nature of dark energy on the formation and evolution of galaxies and on the properties of dark matter.
Durham’s involvement in DESI is led by the Institute for Computational Cosmology (ICC), working with the University’s Centre for Advanced Instrumentation and Centre for Extragalactic Astronomy.
Professor Carlos Frenk, Ogden Professor of Fundamental Physics, in the Institute for Computational Cosmology, at Durham University, said: “Although in the relatively early stages of its mission, DESI is already breaking new ground in producing this map of the universe which is the most detailed we’ve ever seen.
“This will help us to search for clues about the nature of dark energy, but we will also learn more about the dark matter and the role it plays in how galaxies like the Milky Way form and how the universe is evolving. We look forward with huge anticipation to the treasure trove of data that DESI will collect over the next few years. They will help uncover some of the most intimate secrets of the cosmos.”
DESI is already helping scientists reveal the secrets of quasars, a particularly bright variety of galaxies that are among the most powerful and distant objects known. Quasars are excellent in helping scientists probe the early universe because of their sheer power. DESI’s data will go 11 billion years back in time, revealing clues about the evolution of quasars and their connection to the formation of galaxies.
Victoria Fawcett, a PhD researcher in the Centre for Extragalactic Astronomy, in Durham University’s Department of Physics, said: “I like to think of quasars as lampposts, looking back in time into the history of the universe.
“DESI is really great because it is picking up much fainter and redder objects than previously discovered.”
That, Victoria adds, allows scientists to test ideas about quasar evolution that just could not be tested before. And this is not just limited to quasars.
“We’re finding quite a lot of exotic systems,” Victoria said, “including large samples of rare objects that we just haven’t been able to study in detail before.”
Scientists are also using DESI’s data to understand the behavior of intermediate-mass black holes in small galaxies.
Enormous black holes are thought to inhabit the cores of nearly every large galaxy, like the Milky Way, but whether small galaxies always contain their own (smaller) black holes is still not known.
The spectra taken by DESI can help solve this problem. The information DESI can capture and its wide reach across the sky will yield more information about the cores of small galaxies than ever before. This, in turn, will give scientists clues about how quasars formed in the very early universe.
DESI has already catalogued over 7.5 million galaxies and is adding more at a rate of over a million a month. In November 2021 alone, DESI catalogued redshifts from 2.5 million galaxies. By the end of its run in 2026, DESI is expected to have over 35 million galaxies in its catalogue, enabling an enormous variety of cosmology and astrophysics research.
DESI is installed at the Nicholas U Mayall four metre telescope at Kitt Peak National Observatory near Tucson, Arizona, USA.
DESI is supported by the DOE Office of Science and by the National Energy Research Scientific Computing Center, a DOE Office of Science user facility, USA. Additional support is provided by the US National Science Foundation, the Science and Technologies Facilities Council of the United Kingdom, the Gordon and Betty Moore Foundation, the Heising-Simons Foundation, the French Alternative Energies and Atomic Energy Commission (CEA), the National Council of Science and Technology of Mexico, the Ministry of Economy of Spain, and by the DESI member institutions.
The DESI collaboration is honoured to be permitted to conduct scientific research on Iolkam Du’ag (Kitt Peak), a mountain with particular significance to the Tohono O’odham Nation.
News source: Durham University.