Dark matter makes up 27 percent of the universe, yet astronomers have been unable to observe it directly. Dark matter is composed of particles that do not absorb, reflect, or emit light, so they cannot be detected by observing electromagnetic radiation.
Astronomers searching for dark matter in gaps between stars anticipate upcoming images of the Andromeda galaxy may hold vital clues. In particular, gaps in thin streams of stars can reveal disturbances created by dark matter.
The reason why the new information will be revealing is because astronomers currently are limited to studying gaps in the Milky Way galaxy. The new images will come from NASA’s Nancy Grace Roman Space Telescope, which will expand the population of thin stellar streams in nearby galaxies, enabling studies of these gaps. Initial results suggest that gaps in stellar streams should be detectable in Roman images. This insight comes from Northwestern University astrophysicists.
The Roman Space Telescope is set to launch by May 2027 and it will aid in the hunt for dark matter by focusing on the neighbouring Andromeda galaxy, expanding scientific knowledge of thin stellar streams. It is hoped this will generate improved statistics on these gaps and create a better understanding of the possible existence and properties of dark matter clumps.
Existing space- and ground-based telescopes have limited the search to a small number of globular cluster streams within the Milky Way. However, the Roman Space Telescope, which will be located 1 million miles from Earth, will enable astronomers to search nearby galaxies for globular cluster streams for the first time. Roman’s Wide Field Instrument has 18 detectors that will produce images 200 times the size of those produced by the Hubble Space Telescope’s near-infrared camera and at a slightly greater resolution.
Dark matter’s effect is assumed on other galaxies, such as understanding how galaxies rotate, which seems to require extra mass beyond what is visible to explain the rotation. The elongated streams of stars dangling from globular clusters, tightly bound groups of dozens to millions of stars may show clumps of dark matter punching through stellar streams to create gaps. By examining these gaps, astronomers aim to uncover signs of dark matter.
This should lead to a new model of how globular clusters form into stellar streams by developing a much more detailed theoretical framework.
The researchers also plan to examine the halo of dark matter surrounding Andromeda. While dark matter halos encircle all galaxies, including the Milky Way, the researchers suspect they may find evidence of smaller sub-halos, which current models predict.
The initial is published in The Astrophysical Journal, titled “Prospects for Detecting Gaps in Globular Cluster Stellar Streams in External Galaxies with the Nancy Grace Roman Space Telescope.”
