Is the Galactic Missing Matter Mystery Solved?

James Maynard
Feb 5 · 3 min read

Galactic missing matter — one of the greatest mysteries in astrophysics — may have been found by a student astronomer

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Hydrogen snow clouds discovered by Yuanming Wang might explain the mystery of galactic missing matter. Image credit: Cloud: Mark Myers/OzGrav Wang: Louise Cooper

Astronomers have known for decades that around 95 percent of all the mass in the Cosmos consists of dark matter and dark energy. Just five percent of all-there-is can be found as baryonic (normal) matter.

A long standing mystery in astrophysics is that when astronomers add up the masses of every star and cloud of gas they see, it still only adds up to half of the baryonic matter known to exist in the Universe.

“We suspect that much of the ‘missing’ baryonic matter is in the form of cold gas clouds either in galaxies or between galaxies. This gas is undetectable using conventional methods, as it emits no visible light of its own and is just too cold for detection via radio astronomy,” Yuanming Wang, a doctoral candidate in the School of Physics at the University of Sydney explains.

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The ASKAP array of radio telescopes in western Australia. Image credit: CSIRO

Wang and her team developed a method that may allow us to find this galactic missing matter. Researchers utilized the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope in Western Australia to collect data, testing a novel technique.

“ASKAP’s key feature is its wide field of view, generated by its unique chequerboard Phased Array Feed (PAF) receivers. Together with specialised digital systems, a PAF creates 36 separate (simultaneous) beams on the sky which are mosaicked together into a large single image. This gives ASKAP the ability to rapidly survey large areas of the sky — making it one of the world’s fastest survey radio telescopes,” the Commonwealth Scientific and Industrial Research Organisation (CSIRO) reports.

Distant galaxies were used as ‘scintillating pins’ — sparkling lights which serve as beacons. They found five twinkling radio sources in the distant Universe that twinkled like stars in the night sky.

“We conducted an untargeted search over a 30 [degree square] field, with multiple 10-hour observations separated by days to months, at a central frequency of 945 MHz,” researchers describe in the Monthly Notices of the Royal Astronomical Society.

A time-lapse view of the ASKAP radio telescope network. Video credit: CSIRO

The team found the cause of this twinkling — a previously-unseen stream of cold gas just 10 light years from Earth. This stream is roughly 10 trillion kilometers long, and 10 billion kilometers wide. However, this gaseous river contains only as much mass as our Moon.

“We aren’t quite sure what the strange cloud is, but one possibility is that it could be a hydrogen ‘snow cloud’ disrupted by a nearby star to form a long, thin clump of gas,” explains Dr. Artem Tuntsov of Manly Astrophysics.

Researchers theorize that much of the missing baryonic matter in the Universe may consist of these hydrogen snow clouds, which would be nearly impossible to see using traditional methods.

Researchers hope to find additional hydrogen snow clouds around the Cosmos, potentially answering the mystery of the galactic missing matter.

James Maynard is the founder and publisher of The Cosmic Companion. He is a New England native turned desert rat in Tucson, where he lives with his lovely wife, Nicole, and Max the Cat.

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