In addition to the great quest for discovery and explanation, astronomers of dark energy and dark matter have a third task: to discover the missing baryonic (common) matter of the universe, which we expect, but it is not. Now an innovative method has been found that a small part of the missing matter is hidden very close to the solar system (according to astronomical standards), suggesting that such pockets are quite common.
In contrast to dark matter and dark energy, which we know must be fundamentally strange matter apart from the materials we use, the missing matter is ordinary gas and is likely to be somewhat dusty like the universe we see. The problem is that when we first look back at the universe, we can measure the amount of matter present, but observations that are more current seem to have gone halfway through it. Even allowing matter to convert into energy in the stars, there is not as much visible matter as there should be.
In the last few years, astronomers have had considerable success in discovering this lost cause, for example, by identifying large amounts of gas scattered in galaxies millions of light-years away. Yet some are still unaccounted for, some have joked that we have to look at the back of the couch and Yaunming Wang, a student at the University of Sydney, has done the equivalent of astronomy, finding a cloud of unknown matter just 10 or so light-years from Earth.
“This gas is detectable using conventional methods because it does not emit any visible light of its own and is too cold to be detected by radio astronomy,” Wang said in a statement. Wang found it in the blink of an eye. Astronomers have known for some time that certain galaxies glow when viewed by radio telescopes. They conclude that radio waves from galaxies travel through some material, creating an effect comparable to that of starlight flowing through our atmosphere, but not in milliseconds over a period of hours. Wang told IFLScience that it had already proven that the distortions were not coming from our own atmosphere, that we could not see them as products of anything in space.
To investigate this, Wang and colleagues searched a 30-square-degree field to blink galaxies and found six, five in a straight line. Examining other galaxies that are not glowing, they reported that in the Royal Astronomical Society’s monthly notices, these five affected by gas from clouds that are about one trillion kilometers (0.1 light years) long but only 10 billion kilometers wide.
Wang told IFLScience that the gas thought to be hydrogen, since “it was the most misleading element in the universe.” It will certainly feel very cold, or we will be able to detect it in other ways. Wang and co-authors suspect that they found a cloud of “hydrogen snow” that had expanded in its current shape by the gravity of a current star.
“This is the first time multiple ‘scintillators’ have been identified behind a cloud of cold gas. “Over the next few years we should be able to use the same method as the Australian Square Kilometer Array Pathfinder to detect large amounts of gas structures in our galaxy,” said Tara Murphy, Wang’s supervising professor. It is exciting to identify such material very close to home; it fills a small part of the missing substance. Based on its size and the amount of blink of an eye, clouds thought to have the same mass as our own moon.
