Galaxy collision reveals missing matter
* 19:00 10 May 2007
Baby galaxies growing from the debris of a galactic traffic accident have been hiding a lot of extra matter, new observations suggest.
If so, galaxies like our own could contain vast quantities of invisible gas that outweigh their stars and other visible material – and these gas stores could represent some of the "missing" normal matter astronomers have been puzzling over.
... (T)idal dwarf galaxies should only contain a few percent of dark matter.
That is because they form when gas sprayed out in galaxy collisions clumps together under gravity. The unusual properties of dark matter make it difficult for it to clump back together after being disturbed, and simulations show that these newly formed galaxies end up containing little dark matter as a result.
The researchers say the most likely explanation is that the unseen material is mostly hydrogen gas that is only a few degrees above absolute zero. Such cold gas is very difficult to detect.
The work suggests normal galaxies may contain a lot of hidden, cold gas, too, since the dwarf galaxies are just debris stolen from medium-size galaxies like the Milky Way.
"The disc of our galaxy might be two or three times more massive then we actually think it is," team member Elias Brinks of the University of Hertfordshire in Hatfield, UK, told New Scientist.
[More than meets the thermometer...]
Just wanted to share this find because, if the new theory pans out, it'll be just another example of the true nature of misunderstood reality being far simpler than anyone had ever imagined.
It does indeed happen all the time.