Astronomers have for the first time used distant galaxies as ‘scintillating pins’ to locate and identify a piece of the Milky Way’s missing matter.
For decades, scientists have been puzzled as to why they couldn’t account for all the matter in the universe as predicted by theory. While most of the universe’s mass is thought to be mysterious dark matter and dark energy, 5 percent is ‘normal matter’ that makes up stars, planets, asteroids, peanut butter and butterflies. This is known as baryonic matter.
However, direct measurement has only accounted for about half the expected baryonic matter.
Yuanming Wang, a doctoral candidate in the School of Physics at the University of Sydney, has developed an ingenious method to help track down the missing matter. She has applied her technique to pinpoint a hitherto undetected stream of cold gas in the Milky Way about 10 light years from Earth. The cloud is about a trillion kilometers long and 10 billion kilometers wide but only weighing about the mass of our Moon.
The results, published in the Monthly Notices of the Royal Astronomical Society, offer a promising way for scientists to track down the Milky Way’s missing matter.
“We suspect that much of the ‘missing’ baryonic matter is in the form of cold gas clouds either in galaxies or between galaxies,” said Ms Wang, who is pursuing her Ph.D. at the Sydney Institute for Astronomy.