A new simulation shows how NASA’s Nancy Grace Roman Space Telescope will turn back the cosmic clock when it is launched in May 2027, revealing the evolution of the universe in ways never before possible. With her ability to rapidly image vast swaths of space, Roman will help us understand how the universe transformed from a primeval sea of charged particles to the intricate web of vast cosmic structures we see today.
“The Hubble and James Webb Space Telescopes are optimized for studying astronomical objects deep and up close, so they’re like looking at the universe through a tiny hole,” said Aaron Yung, a postdoctoral fellow at the Goddard Space Flight Center at the NASA in Greenbelt, Maryland, who led the study. “To solve cosmic mysteries on the largest scales, we need a space telescope that can show a much broader view. That’s exactly what Roman is designed to do.”
Combining Roman’s grand vision with Hubble’s broader wavelength coverage and Webb’s more detailed observations will provide a more complete picture of the universe.
The simulation covers a two-square-degree section of sky, which is about 10 times the apparent size of a full moon and contains more than five million galaxies. The simulation is based on a model of galaxy formation that has been extensively tested and represents our current understanding of how the universe works. Using an extremely efficient technique, the team can simulate tens of millions of galaxies in less than a day, something that could take years using conventional methods. When Roman launches and begins streaming real data, scientists will be able to compare that data to a variety of such simulations to test their models. That will help unravel the physics of galaxy formation, dark matter—a mysterious substance observed only through its gravitational effects—and much more.
A scientific article describing these results was published in The Monthly Notices of the Royal Astronomical Society of England in December 2022.
In this simulated view of the deep cosmos, each dot represents a galaxy. The three small squares show Hubble’s field of view, and each one reveals a different region of the synthetic universe. Roman will be able to quickly scan an area as large as the entire zoomed-in image, giving us insight into the largest structures in the universe.
Credits: NASA Goddard Space Flight Center and A. Yung
Unravel the cosmic web
Galaxies and clusters of galaxies glow in groups along invisible threads of dark matter, in a tapestry the size of the observable universe. With a wide enough view of that tapestry, we can see that the large-scale structure of the universe is like a web, with threads stretching hundreds of millions of light-years. Galaxies are found mostly at the intersections of the filaments, with vast “cosmic voids” between all the bright threads.
This is what the cosmos looks like now. But if we could go back the universe in time, we would see something very different.
Instead of giant, fiery stars scattered in galaxies separated by even more immense distances, we would find ourselves submerged in a sea of plasma (charged particles). This primordial broth was almost completely uniform, but luckily for us, there were little ‘lumps’. Since those clumps were slightly denser than their surroundings, they had a slightly greater gravitational pull.
Over hundreds of millions of years, the accumulations attracted more and more material. They grew large enough to form stars, which were gravitationally pulled into the dark matter that forms the invisible backbone of the universe. Galaxies were born and continued to evolve, and planetary systems like ours eventually arose.
Roman’s panoramic view will help us see what the universe was like at different stages and fill in many gaps in our understanding. For example, although astronomers have discovered “halos” of dark matter that surround galaxies, they are not sure how they formed. By seeing how gravitational lensing caused by dark matter distorts the appearance of objects further away, Roman will help us understand how halos developed over cosmic time.
“Simulations such as these will be instrumental in connecting the unprecedented large galaxy surveys to be carried out by the Roman telescope with the invisible scaffolding of dark matter that determines the distribution of these galaxies,” said Sangeeta Malhotra, an astrophysicist at the Goddard Center and co-author of the study. scientific article.
See the bigger picture
Studying such vast cosmic structures with other space telescopes is impractical because it would take hundreds of years of observations to stitch together enough images to see such structures.
“Roman will have the unique ability to match the depth of Hubble’s ultra-deep field, while covering an area of sky several times larger than wide surveys like the CANDELS survey,” Yung said. “Such a comprehensive view of the early universe will help us understand how representative the images captured by Hubble and Webb are of what it was like back then.”
Roman’s broad vision will also serve as a road map that Hubble and Webb could use to focus on interesting areas.
The extensive surveys of the sky that will be carried out by the Roman telescope will be able to map the universe up to a thousand times faster than Hubble. That will be possible due to the rigid structure of the observatory, its fast rate of rotation and the large field of view of the telescope. Roman will quickly move from one cosmic target to the next. Once a new target is acquired, the vibrations will quickly cease because potentially unstable structures, such as solar panels, are fixed in place.
“Roman will take about 100,000 pictures each year,” said Jeffrey Kruk, a research astrophysicist at Goddard. “Given Roman’s larger field of view, even for powerful telescopes like Hubble or Webb, it would take longer than our lives to cover such a large area of sky.”
By offering a gigantic, sharp view of cosmic ecosystems and by working with observatories like Hubble and Webb, Roman will help us solve some of the deepest mysteries in astrophysics.
The Nancy Grace Roman Space Telescope is managed at NASA’s Goddard Space Flight Center with the participation of NASA’s Jet Propulsion Laboratory (JPL) and Caltech/IPAC in Southern California, the Space Telescope Science Institute in Baltimore and a scientific team made up of scientists from various research institutions. Major industrial partners are Ball Aerospace and Technologies Corporation in Boulder, Colorado; L3Harris Technologies in Melbourne, Fla.; and Teledyne Scientific & Imaging in Thousand Oaks, California.
By Ashley Balzer
NASA Goddard Space Flight Center, Greenbelt, Maryland
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