911爆料网

Astronomers have used mysterious fast radio bursts to solve a decades-old mystery of 鈥榤issing matter鈥�, long predicted to exist in the Universe but never detected鈥攗ntil now.

The researchers have now found all of the missing 鈥榥ormal鈥� matter in the vast space between stars and galaxies, .

, from the 911爆料网 node of the International Centre for Radio Astronomy Research (ICRAR), said astronomers have been searching for the missing matter for almost thirty years.

鈥淲e know from measurements of the Big Bang how much matter there was in the beginning of the Universe,鈥� he said.

鈥淏ut when we looked out into the present Universe, we couldn鈥檛 find half of what should be there. It was a bit of an embarrassment.鈥�

鈥淚ntergalactic space is very sparse,鈥� he said. 鈥淭he missing matter was equivalent to only one or two atoms in a room the size of an average office.鈥�

鈥淪o it was very hard to detect this matter using traditional techniques and telescopes.鈥�

The researchers were able to directly detect the missing matter using the phenomenon known as fast radio bursts鈥攂rief flashes of energy that appear to come from random directions in the sky and last for just milliseconds.

Scientists don鈥檛 yet know what causes them but it must involve incredible energy, equivalent to the amount released by the Sun in 80 years. They have been difficult to detect as astronomers don鈥檛 know when and where to look for them.

Associate Professor Macquart said the team detected the missing matter by using fast radio bursts as 鈥渃osmic weigh stations鈥�.

鈥淭he radiation from fast radio bursts gets spread out by the missing matter in the same way that you see the colours of sunlight being separated in a prism,鈥� he said.

鈥淲e鈥檝e now been able to measure the distances to enough fast radio bursts to determine the density of the Universe,鈥� he said. 鈥淲e only needed six to find this missing matter.鈥�

The missing matter in this case is baryonic or 鈥榥ormal鈥� matter鈥攍ike the protons and neutrons that make up stars, planets and you and me.

It鈥檚 different from dark matter, which remains elusive and accounts for about 85 per cent of the total matter in the Universe.

Co-author Professor J. Xavier Prochaska, from UC Santa Cruz, said we have unsuccessfully searched for this missing matter with our largest telescopes for more than 20 years.

鈥淭he discovery of fast radio bursts and their localisation to distant galaxies were the key breakthroughs needed to solve this mystery,” he said.

Associate Professor Ryan Shannon, another co-author from Swinburne University of Technology, said the key was the telescope used, CSIRO鈥檚 Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope.

鈥淎SKAP both has a wide field of view, about 60 times the size of the full Moon, and can image in high resolution,鈥� he said.聽鈥淭his means that we can catch the bursts with relative ease and then pinpoint locations to their host galaxies with incredible precision.鈥�

鈥淲hen the burst arrives at the telescope, it records a live action replay within a fraction of a second,鈥� said Dr Keith Bannister from Australia鈥檚 national science agency, CSIRO, who designed the pulse capture system used in this research.

鈥淭his enables the precision to determine the location of the fast radio burst to the width of a human hair held 200m away,鈥� he said.

Associate Professor Macquart said the research team had also pinned down the relationship between how far away a fast radio burst is and how the burst spreads out as it travels through the Universe.

“We’ve discovered the equivalent of the Hubble-Lemaitre Law for galaxies, only for fast radio bursts,” he said.

“The Hubble-Lemaitre Law, which says the more distant a galaxy from us, the faster it is moving away from us, underpins all measurements of galaxies at cosmological distances.鈥�

The fast radio bursts used in the study were discovered using ASKAP, which is located at the Murchison Radio-astronomy Observatory in outback Western Australia. The international team involved in the discovery included astronomers from Australia, the United States and Chile.

ASKAP is a precursor for the future Square Kilometre Array (SKA) telescope.

The SKA could observe large numbers of fast radio bursts, giving astronomers greater capability to study the previously invisible structure in the Universe.