New computer simulations indicate that a faint radio signal from the early universe's dark ages could carry detectable traces of dark matter. Researchers from Japanese universities predict variations in this 21-centimeter signal that might reveal properties of the invisible substance. Lunar radio telescopes may soon capture these echoes to probe cosmic mysteries.
The universe originated 13.8 billion years ago in the Big Bang, an explosive expansion that set the stage for cosmic evolution. About 400,000 years later, as the cosmos cooled and atoms formed, it entered the Dark Ages—a 100-million-year period of obscurity before the first stars lit up the void.
During this silent epoch, hydrogen atoms are believed to have emitted subtle radio waves at a 21-centimeter wavelength. These faint signals, preserved across billions of years, offer a window into the universe's infancy. A team from the University of Tsukuba and the University of Tokyo has used advanced supercomputer simulations to model how these emissions might interact with dark matter, which constitutes roughly 80 percent of the universe's matter yet remains undetected directly.
The models forecast an average brightness temperature for the signal of about 1 millikelvin across the sky. Dark matter's influence could introduce fluctuations of comparable magnitude, providing clues to the particles' mass and velocity. By observing the signal over a broad frequency band around 45 MHz, astronomers hope to decode these patterns.
Earth-based detection proves challenging due to atmospheric and technological noise. Hence, attention turns to the moon, where missions like Japan's Tsukuyomi Project plan to deploy radio telescopes in the interference-free environment. Success here could illuminate dark matter's role in the universe's formation.
The findings appear in Nature Astronomy, highlighting the 21-centimeter signal's potential as a tool for cosmology.