Dev R. Sadaula

At the heart of galaxy 1ES 1927+654, a black hole behaves like a lighthouse with a faulty mechanism. Every six and a half minutes, it releases a burst of X-ray light, a rhythm astronomers have been tracking since 2022. At first, the beacon's tempo wandered — speeding up and slowing down, with intervals ranging from one beat every eighteen minutes to one every seven.

For years, silence reigned in the heart of galaxy 1ES 1927+654: the accreting gas merely whispered in X-rays, leaking slow winds. But in 2022–2025, the picture changed dramatically. Spectra taken by XMM-Newton and Swift lit up with emission lines — a narrow peak at 0.56 keV, likely from OVII oxygen, a broader feature near 1 keV, and a powerful iron band in the 6–7 keV region.