Astronomers from the California Institute of Technology and the Harvard Center for Astrophysics have found the missing half of visible matter in the universe. They also managed to detect the most distant fast radio burst ever recorded.
Unlike dark matter, ordinary (baryonic) matter participates in electromagnetic interactions and is visible. However, approximately half of it remained unaccounted for over decades. Astronomers used methods such as X-ray and ultraviolet observations of distant quasars to find traces of huge amounts of this missing mass in the form of hot gas between galaxies. However, due to its very low density, it remained invisible to most telescopes. As a result, scientists could only estimate, but not confirm, its exact quantity and location.
To solve the problem of missing matter, scientists used fast radio bursts: short, bright radio signals from distant galaxies. They act as cosmic flashlights, shining through the fog of the intergalactic medium. By accurately measuring how light slows down, astronomers can weigh this fog, even if it is too faint to be seen.
In their study, scientists analyzed 69 radio bursts located at distances ranging from 11.74 million light-years (in the nearby galaxy M81) to 9.1 billion light-years from Earth. The latest burst, designated FRB 20230521B, was the most distant ever recorded.
Analysis of the data obtained shows that approximately 76% of the baryonic matter in the universe is located in intergalactic space, about 15% in galactic halos, and the remaining small portion in stars or among cold galactic gas. This distribution corresponds to the predictions of modern cosmological simulations, but has never been directly confirmed until now.
According to scientists, this discovery is a triumph of modern astronomy, allowing us to see the structure and composition of the universe in a completely new light. The search for missing baryons is not just a theoretical exercise in conducting a cosmic census. Their distribution is key to unlocking profound mysteries about how galaxies form, how matter accumulates in the universe, and how light travels across billions of light-years.
As new-generation radio telescopes are commissioned, astronomers will be able to detect thousands of new radio bursts. This will enable them to create an incredibly detailed map of the cosmic web in the future.
According to Phys.org
