Though dark matter appears to be common in the universe, there’s still a lot we don’t know about it. A new study has now shed some light on this mysterious topic using faint satellite galaxies around the Milky Way.
Prolific Yet Unseen
The relative amounts of the different constituents of the universe. Dark matter makes up roughly 27%. [ESA/Planck]Our universe is composed almost entirely of dark energy, dark matter, and ordinary matter. While ordinary matter makes up a scant 5% of the universe, dark matter appears to be more common, accounting for 27%. But while dark matter reveals itself through its gravitational effects — adding bulk to galaxy halos that helps hold galaxies together and changes how they move, for instance — we’ve yet to detect it directly.
This challenge means that we’re still working to understand the nature of this unseen substance. Is dark matter made up of primordial black holes? An as-yet undiscovered subatomic particle? Or something else entirely?
Strong gravitational lensing like that observed in this image of Abell 1689 provides evidence for dark matter, but we still don’t understand its nature. [NASA/N. Benitez/T. Broadhurst/H. Ford/M. Clampin/G. Hartig/G. Illingworth/the ACS Science Team/ESA]
The Hunt for the ...