Mysterious dark matter may leave clues in 'strings of pearls' trailing our galaxy

By Sharmila Kuthunur published 8 hours ago

"If we find a pearl necklace with a few scattered pearls nearby, we can deduce that something may have come along and broken the string."



Stellar streams in and around the Milky Way could reveal clues about the nature of dark matter. (Image credit: RubinObs/NOIRLab/NSF/AURA/J. daSilva, M. Zamani)

Starting late next year, the Vera C. Rubin observatory, a $700-million telescope nearing completion in northern Chile, plans to gather clues about the nature of dark matter by studying gaps between streams of stars that orbit at the outskirts of our galaxy.

These gaps are found within starry trails left behind after the Milky Way gravitationally shredded nearby galaxies, within which the stellar remnants exist. These are useful tracers of dark matter  —  the invisible, universe-permeating substance that surrounds most galaxies in halos but is yet to be directly detected. In stellar streams, the influence of dark matter can be inferred "in the same way that twinkle lights can reveal the shape of a tree that they are strung up around, even when we can't see the branches or foliage," scientists say.

"Stellar streams are like strings of pearls, whose stars trace the path of the system's orbit and have a shared history," Jaclyn Jensen, a graduate student at the University of Victoria in British Columbia, said in a statement. "If we find a pearl necklace with a few scattered pearls nearby, we can deduce that something may have come along and broken the string."

A key prediction of the standard cosmological model, which is based on the assumption that dark matter is "cold" (meaning it has very weak interactions with ordinary matter and electromagnetic radiation), is that dark matter is made up of smaller clumps. When these clumps interact with other structures, scientists believe they disrupt the dynamics of those structures and even alter their appearance.

More:
https://www.space.com/rubin-observatory-dark-matter-strings-pearls-milky-way-galaxy