'The beacons were lit!' Scientists name merging supermassive black holes after 'Lord of the Rings' locations

Scientists have identified two merging supermassive black hole binaries named Gondor and Rohan, inspired by locations in J.R.R. Tolkien’s "Lord of the Rings." These systems were discovered using a novel technique that combines the detection of gravitational waves—ripples in spacetime—with observations of quasars, the luminous centers of galaxies powered by supermassive black holes. The binaries, designated SDSS J0729+4008 (Gondor) and SDSS J1536+0411 (Rohan), were found by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) team, marking a significant advance in identifying these cosmic phenomena. The new method leverages the fact that supermassive black hole binaries emit gravitational waves of increasing frequency as they spiral closer before merging. Quasars, which are five times more likely to host these binaries, act as beacons signaling the presence of such systems. By detecting gravitational wave signals from these quasars, scientists can map the locations of merging black holes across the universe. This approach provides a promising way to develop a comprehensive catalog of supermassive black hole mergers and to refine detection protocols for continuous gravitational wave sources. NANOGrav’s discovery builds on their 2023 detection of a gravitational wave background, a faint hum created by numerous merging black holes. The team analyzed 114 active galactic nuclei (AGNs), where supermassive black holes consume surrounding matter, to identify these binaries. The names Gondor and Rohan honor both pop culture and contributors to the research, with Rohan named after a Yale student involved in the analysis. This work is expected to enhance understanding of galaxy mergers, black hole physics, and gravitational wave characteristics. Looking ahead, NANOGrav plans to expand its search for supermassive black hole binaries, aiming to create a detailed gravitational wave background map. This research not only opens new avenues for astrophysical exploration but also lays the groundwork for systematic detection frameworks that could transform how scientists study the universe’s most massive and energetic events.