Pulsar Observations Could Reveal Gravitational Wave Interference From Black Holes

Astronomers may soon be able to “hear” gravitational-wave beats through the rhythmic pulses of distant neutron stars. A new study suggests that subtle timing shifts in pulsars—nature's most precise cosmic clocks—could reveal interference between gravitational waves of nearly identical frequencies, offering a fresh way to trace supermassive black hole pairs across the universe. The research could help determine whether last year's detected ultra-low-frequency signals come from many distant sources or a nearby binary system.

Pulsar Timing May Reveal Gravitational-Wave ‘Beats' from Merging Supermassive Black Holes

According to findings published in the Journal of Cosmology and Astroparticle Physics, theoretical physicist Hideki Asada and researcher Shun Yamamoto from Hirosaki University proposed the method after analysing pulsar timing data.

They suggest that when two supermassive black hole binaries emit waves at almost the same frequency, their interference produces a “beat pattern”, which can appear as periodic variations in pulsar timing. Detecting these patterns would allow to weed out sources against a background cosmic appearance in nature

Indeed, a handful of international collaborations, such as NANOGrav and some European groups with which Asada is involved but cannot publicly discuss at this time. They have already seen strong hints of nanohertz gravitational waves — albeit not with the high-significance five-sigma discovery threshold. When it is confirmed, scientists think the next step is to trace out exactly where these ripples in spacetime are coming from.

The proposed technique could become crucial as observatories refine pulsar data in the coming years. Scientists anticipate that confirmed detections will not only validate these faint cosmic rhythms but also reveal new insights into the merging of distant galaxies.