Astronomers Find 3rd Dark-Matter-Free Galaxy 67 Million Light-Years Away
Updated
Updated · ScienceAlert · Jun 20
Astronomers Find 3rd Dark-Matter-Free Galaxy 67 Million Light-Years Away
3 articles · Updated · ScienceAlert · Jun 20
Summary
NGC 1052-DF9, 67 million light-years from Earth, has become the third known galaxy whose motions can be explained without dark matter, according to a study in The Astrophysical Journal.
DF9 was targeted because it closely matches the earlier anomalies DF2 and DF4 and sits in the same linear chain of about a dozen galaxies, where researchers had predicted more dark-matter-free objects might turn up.
Michael Keim's team said the trio offers some of the clearest evidence yet that the galaxies formed together in a violent event that separated ordinary matter from dark matter.
One leading explanation is a "bullet dwarf collision," in which gas from two colliding dwarf galaxies stalls while stars and dark matter pass through, leaving baryon-rich material that can form galaxies with little or no dark matter.
The finding matters because dark matter outweighs ordinary matter by about 5 to 1, and the unusual chain could help test whether dark matter is a physical substance rather than an alternative gravity effect.
An entire trail of galaxies lacks dark matter. Does this finally prove our theory of the universe is wrong?
A cosmic collision created galaxies without dark matter. So where did all the missing dark matter go?
DF9 and the Chain of Dark Matter-Poor Galaxies: A New Challenge to Cosmology
Overview
The discovery of NGC 1052-DF9 (DF9), identified by Yale astronomers, marks a major challenge to our understanding of the universe. DF9 is the third known galaxy with little to no dark matter, joining DF2 and DF4. What makes these galaxies especially intriguing is their linear arrangement with several others, all showing a striking lack of dark matter. This unusual alignment raises important questions about how galaxies form and the true nature of dark matter, pushing scientists to rethink established cosmological models and explore new ideas about the structure of the cosmos.