Chinese Scientists Reveal Clues Behind Declining Star Formation
Muhammad Irfan
Published: September 03, 2026 | Time: 04:00 PM
BEIJING, (UrduPoint / Pakistan Point News / WAM - 03rd Sep, 2026)
Chinese scientists using the Five-hundred-meter Aperture Spherical Telescope (FAST) and the Dark Energy Spectroscopic Instrument (DESI) have made a significant discovery. They found that while star formation has declined sharply over the past 4.5 billion years, the universe's neutral atomic hydrogen reservoir has remained relatively stable.
According to a Global Times report, these findings offer valuable insights into why galaxies are becoming less efficient at forming stars.
The question of why the universe is producing fewer new stars remains a central mystery in galaxy research. One theory suggests that galaxies have depleted their supply of cold gas needed for star formation. If this were the case, the amount of cold gas should have decreased at a similar rate.
Neutral atomic hydrogen is a crucial source of this gas, but its weak 21-centimeter radio signal makes it challenging to observe, especially from distant galaxies.
To overcome this challenge, researchers combined sensitive radio observations from FAST with data from DESI's large-scale galaxy survey, studying approximately 2.5 million galaxies across one-third of the sky. By combining weak signals from numerous galaxies based on their redshifts, they detected an average neutral hydrogen signal that could not be observed in individual galaxies.
The results revealed that around 4.5 billion years ago, the universe's star formation rate was approximately 2.5 times higher than today, while the density of neutral hydrogen was only about 1.4 times higher. This indicates that star formation has declined much faster than the supply of neutral hydrogen, suggesting that the universe is not simply running out of gas for star formation.
Instead, these findings raise a more fundamental question: why are galaxies becoming less efficient at converting their remaining neutral hydrogen into new stars?
The study provides a crucial clue to understanding the gradual decline of star formation and the evolution of galaxies across the universe.
Conducted by an international team including researchers from the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC), Shanghai Astronomical Observatory (SHAO) of the Chinese Academy of Sciences, Shanghai Jiao Tong University, and other institutions.