New study reveals, for the first time, a tidal disruption event (TDE), where a black hole tears apart a star, occurring outside the center of a galaxy that produced exceptionally strong and rapidly evolving radio signals. This rare discovery shows that supermassive black holes can exist and remain active far from galactic cores, challenging current understanding of where such black holes reside and how they behave. The event’s delayed and powerful radio outbursts also suggest previously unknown processes in how black holes eject material over time.

Pulsars suggest that ultra–low-frequency gravitational waves are rippling through the cosmos. The signal seen by international pulsar timing array collaborations in 2023 could come from a stochastic gravitational-wave background—the sum of many distant sources—or from a single nearby binary of supermassive black holes. To tell these apart, Hideki Asada, theoretical physicist and Professor at Hirosaki University, and Shun Yamamoto, researcher at the Graduate School of Science and Technology, Hirosaki University, propose a method that exploits beat phenomena between gravitational waves at nearly the same frequency, searching for their imprint in the tiny shifts of pulsars’ radio-pulse arrival times.