NANOGrav Discovers Two Supermassive Black Hole Binaries: Gondor and Rohan

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has discovered two supermassive black hole binaries, designated SDSS J0729+4008 (Gondor) and SDSS J1536+0411 (Rohan).

This discovery utilized a new technique that combines observations of quasars with the background hum of gravitational waves.

A Novel Discovery Method

Supermassive black hole binaries are systems of two black holes spiraling towards a merger. As their orbits shrink, these systems emit gravitational waves of increasing frequency.

Quasars, which are powered by feeding supermassive black holes, are approximately five times more likely to host these mergers.

This method allows quasars to function as indicators for the presence of unifying supermassive black holes, enabling scientists to map these merging systems.

Research Insights and Future Implications

NANOGrav team member Chiara Mingarelli stated that this finding provides a crucial step forward for the scientific community. "This finding provides the scientific community with the first concrete benchmarks for developing and testing detection protocols for individual, continuous gravitational wave sources," Mingarelli noted.

Mingarelli and her colleagues applied this new approach to 114 Active Galactic Nuclei (AGNs), which are bright central regions of galaxies where supermassive black holes are actively feeding.

The black hole systems were named Gondor and Rohan. Rohan was named after Yale student Rohan Shivakumar, who first analyzed it, with Gondor following due to the significance of the detection.

NANOGrav, which initially detected a gravitational wave background in 2023, plans to continue identifying supermassive black hole binaries.

A catalog of these mergers could contribute to creating a gravitational wave background map and significantly enhance understanding of galaxy mergers, black hole physics, and gravitational waves.