NASA’s upcoming Roman telescope to search for signs of dark matter clumps

Following the launch of the Nancy Grace Roman Space Telescope by May 2027, astronomers will use its vast, exquisitely detailed images to spot globular cluster streams in nearby galaxies for the first time. Specifically, they will focus on the tidal streams in our neighbour, the Andromeda galaxy, to identify more of these streams and ultimately pinpoint more properties of dark matter - a mysterious substance that makes up approximately 27% of the total mass and energy content of the universe.

Until now, astronomers have been able to study a limited number of globular cluster streams within our home galaxy - the Milky Way - using both ground and space-based observatories.

Andromeda is similar in size and structure to our Milky Way galaxy but is more massive. The lengths of globular cluster streams in our Milky Way galaxy vary wildly. Short stellar streams are considered relatively young whereas longer streams that wrap around a galaxy can be much older, possibly dating back to the early stages of the universe. Astronomers believe that a stream that is fully wrapped around Andromeda could be more than 300,000 light-years long but less than 3,000 light-years wide.

The Wide Field Instrument onboard the Roman telescope has 18 detectors that will produce images 200 times the size of the NASA/ESA Hubble Space Telescope's near-infrared camera - at a slightly greater resolution.

"Roman will be able to take a huge snapshot of the Andromeda galaxy, which simply isn't possible with any other telescope. We also project that Roman will be able to detect stars individually," says Christian Aganze, the lead author of a recent paper about this subject and a postdoc at Stanford University in California.

"We expect dark matter to interact with globular cluster streams. If these sub-halos are present in other galaxies, we predict that we will see gaps in globular cluster streams that are likely caused by dark matter," says Tjitske Starkenburg, a co-author and a research assistant professor at Northwestern University in Evanston, Illinois.