The JWST Ultramassive Galaxy Sample -- II. Supermassive Black Hole Masses for 8 Extreme Early-Type Galaxies via Jeans Anisotropic Modelling of High-Resolution Integral-Field NIRSpec Stellar Kinematics — E8 Intelligence Research
Year: 2026
Type: preprint
Abstract: We present central supermassive black hole (BH) mass measurements for the JWST Ultramassive Galaxy Sample, comprising 8 galaxies selected from a complete sample of the most massive early-type galaxies in the nearby Universe ($M_\star \gtrsim 2\times10^{12} M_\odot$). Building on the MGE photometric profiles and JWST/NIRSpec stellar kinematics from Paper I, we use the Jeans Anisotropic Modelling (JAM) framework to reconstruct the nuclear dynamics. Given the unique structural properties of these dry-merger-dominated systems, our Bayesian MCMC analysis explicitly tests both oblate and prolate intrinsic geometries. By marginalizing over classical dynamical degeneracies (including orbital velocity anisotropy, mass-to-light ratios, and inclination), we extract robust BH masses. We demonstrate that JWST's exceptional resolution allows JAM to tightly constrain the central potential using nuclear kinematics alone. Crucially, not all ultramassive galaxies host ultramassive BHs: while most displa Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com
Source: arXiv (Cornell University)
Author: Caldin, Andrew Stewart
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7213988545