Overview
- Using triaxial Schwarzschild models on 16 bright cluster galaxies, a Munich team reports that stellar velocity dispersion saturates at ultramassive scales, breaking the traditional M–sigma relation.
- The researchers directly measured eight ultramassive black holes exceeding roughly ten billion solar masses, suggesting past methods likely underestimated the biggest objects.
- The study proposes the photometric radius of a galaxy’s depleted core from merger-driven core scouring as a more reliable proxy for extreme black-hole mass.
- Exceptions, including a massive black hole in Abell 2107 without a depleted core, highlight diverse growth histories and the authors note the findings are presented as an arXiv preprint.
- In parallel, XRISM with NuSTAR and XMM-Newton delivered the most detailed X-ray spectrum of MCG-6.30-15, estimating a ~2 million-solar-mass black hole, resolving near-horizon gas and at least five wind zones, and initiating plans to reassess spin measurements with higher-resolution data.