FAST telescope findings challenge theories on cosmic star formation decline

An international research team has discovered that the decline in the universe’s star formation rate is not caused by a rapid depletion of neutral hydrogen. Using data from the Five-hundred-meter Aperture Spherical radio Telescope (FAST) and the Dark Energy Spectroscopic Instrument (DESI), scientists analyzed approximately 2.5 million galaxies to trace cosmic evolution over the last 4.5 billion years.

The study, published in Nature Astronomy, reveals a significant discrepancy between star formation and hydrogen availability. While the cosmic star formation rate has dropped by a factor of approximately 2.46 over this period, the density of neutral atomic hydrogen has declined much more modestly, by a factor of only about 1.35.

These findings challenge the long-held hypothesis that galaxies are simply running out of the raw material needed for star birth. Instead, the research suggests that the slowdown in star formation may be due to decreasing efficiency in converting neutral hydrogen into the dense molecular gas that directly fuels the process.