Astronomers discover third galaxy with little to no dark matter
HONOLULU (HawaiiNewsNow) – Astronomers have discovered a third galaxy that appears to contain little to no dark matter.
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Using the W. M. Keck Observatory on Maunakea, researchers identified the newly found galaxy, known as DF9, which joins two previously discovered galaxies — DF2 and DF4 — that have puzzled scientists because they appear to be missing the invisible substance believed to make up much of the universe’s mass.
Researchers said the three galaxies are aligned in a narrow structure stretching across space, suggesting they may have formed together during a violent collision between galaxies.
“Almost every galaxy in the universe is dominated by dark matter. But DF2, DF4, and now DF9 appear to be extraordinary exceptions,” said Michael Keim, lead author of the study and a researcher at Yale University.
Scientists believe the galaxies may have formed after a high-speed collision stripped ordinary matter away from surrounding dark matter, allowing new galaxies to develop with little or none of the material.
The findings provide new evidence that dark matter behaves as a physical substance and could help researchers better understand how galaxies form and evolve.
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Using the Keck Cosmic Web Imager, astronomers measured the motions of stars within DF9 and found the galaxy’s mass to be consistent with its visible matter alone.
Researchers said that if DF9 contained a typical amount of dark matter, it would be expected to be roughly 100 times more massive.
The study, led by Yale University, was published Monday in The Astrophysical Journal.
Future observations will focus on searching for gas that may have been left behind by the suspected galactic collision and further investigating how the unusual galaxies formed.
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