NANOGrav detects ultra-low-frequency gravitational wave background

Researchers using the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) have detected an ultra-low-frequency gravitational wave background. By monitoring pulsars—rapidly spinning neutron stars that act as cosmic clocks—for 15 years, scientists identified a continuous cosmic “hum” caused by ripples in space-time.

The detected signal is approximately twice as loud as expected. The primary explanation is that these waves originate from pairs of supermassive black holes spiraling toward one another in massive cosmic collisions. The unexpected volume of the background suggests either a higher abundance of heavy supermassive black holes or phenomena predicted by string theory.

Further research from Colgate University is investigating the origins of these massive black holes. Scientists are exploring whether the signal could be linked to ancient “Dark Stars”—hypothetical objects that may have existed over 13 billion years ago—which could have served as the seeds for the supermassive black holes observed in the early universe.