XRISM provides sharpest X-ray view yet of a rapidly spinning black hole

XRISM, together with XMM-Newton and NuSTAR, produced the sharpest X‑ray spectrum of the Seyfert galaxy MCG‑6‑30‑15 and isolated a broadened iron emission line that indicates material orbiting close to its supermassive black hole.

XRISM, a joint JAXA–NASA X‑ray observatory launched on Sept. 7, 2023, has produced the sharpest X‑ray spectrum yet of the Type 1 Seyfert galaxy MCG‑6‑30‑15. Researchers combined XRISM’s Resolve instrument data with observations from ESA’s XMM‑Newton and NASA’s NuSTAR to separate spectral features that were previously blended. The team, led by Laura Brenneman of the Harvard & Smithsonian Center for Astrophysics, reports a broadened iron emission line and associated X‑ray reflection consistent with material orbiting very close to the galaxy’s supermassive black hole. That black hole is reported to be about 2 million solar masses and lies roughly 120.7 million light‑years from Earth. Key findings: - XRISM, together with XMM-Newton and NuSTAR, produced the sharpest-ever X‑ray spectrum of MCG‑6‑30‑15. - The team isolated a broadened iron emission line and associated reflection that point to rapidly orbiting material near the black hole’s event horizon. - High spectral resolution allowed separation of emission and absorption from the inner accretion disk and more distant gas, showing the inner region produces about 50 times as much X‑ray reflection as distant gas clouds. - The study reports new information about the black hole’s corona, described as a billion-degree region above and below the accretion disk, and identifies at least five distinct zones in an accretion-driven wind. - The main study appeared in The Astrophysical Journal, and a companion study led by co-author Daniel R. Wilkins has been submitted for further analysis of time-dependent spectra. Summary: The new XRISM-enabled spectrum strengthens evidence that much of the observed X‑ray emission in MCG‑6‑30‑15 comes from gas orbiting close to its supermassive black hole and provides higher-resolution measurements that can help refine spin estimates reported from earlier, lower-resolution data. The researchers have also reported more detailed structure in the corona and accretion-driven wind, and follow-up analysis of time-varying spectra is reported as underway or submitted for publication.