Overview
- A team led by Silke Britzen reports to the Monthly Notices of the Royal Astronomical Society evidence of two supermassive black holes in Markarian 501 based on 23 years of radio observations.
- The data reveal a second, faint jet that moves around the brighter, Earth‑pointing jet and, in June 2022, formed an Einstein‑ring image consistent with gravitational lensing.
- The researchers estimate an orbital period of about 121 days with a separation of roughly 250 to 540 astronomical units and masses between 100 million and 1 billion Suns.
- They say a merger could occur in about a century if the pair is at the closer end of the range, though that timing remains uncertain.
- No telescope can resolve two accretion disks at this distance, so teams will seek very low‑frequency gravitational waves with long‑term pulsar timing to independently confirm the binary and test ideas about how giant black holes grow.