By detecting radio wave pulses from distant explosions, astronomersgalaxyA large amount of previously unobserved matter has been located in the vast void. Researchers recently published a report in Nature Astronomy stating that more than three-quarters of the normal atomic matter in the universe is hidden in these intergalactic spaces in the form of thin clouds of warm gas, solving the "missing baryons (including particles such as neutrons and protons) problem" that has plagued the scientific community for more than two decades.
In the past, there was a significant gap between the total mass of stars, galaxies and gas clouds observed by astronomers and the total amount of baryons predicted by the Big Bang theory. Only 5% of the universe is baryonic matter (such as stars, planets and other visible matter), and the remaining 68% is dark energy and 27% is dark matter. The observation of fast radio bursts (FRB) fills this gap. The vast majority of fast radio bursts last only a few milliseconds to a few seconds, and most are one-time events, while a few reoccur irregularly. These brief, intense bursts of radio waves originate from distant galaxies, possibly produced by compact objects such as magnetars. As they travel through intergalactic space, they interact with electrons in the gas, causing signal dispersion. By analyzing this dispersion, scientists can calculate the total amount of gas along the way.
By deploying a wide array of radio telescopes, astronomers can capture enough pulse signals to accurately track the location of their source galaxy.
In 2020, Australia's "Square Kilometer Array Pathfinder (ASKAP)" telescope used a small amount of fast radio burst data to estimate the total amount of baryonic matter for the first time, but it was unable to pinpoint its distribution. The latest research is based on 69 located fast radio bursts (including one about 9 billion light-years away), 39 of which were accurately captured by the American fast radio burst detection device "Deep Synchronization Optical Array 110" (DSA-110).
The results show that 76% of the baryon matter is distributed in interstellar warm gas clouds, 15% is the cold gas around the galaxy, and only 9% constitutes stars, planets and all celestial bodies. This distribution shows that galaxies expel gas through supernova explosions or black hole activity, forming a "galaxy feedback" mechanism. This discovery is crucial to understanding the evolution of galaxies.
Scientists are looking to the next step in accurately mapping the filaments of intergalactic gas that theorists call the 'cosmic web'. Some researchers believe that once the radio array can locate thousands of fast radio bursts, this goal is expected to be achieved.