A Stellar Dynamical Mass Measurement of the Supermassive Black Hole in NGC 3258

TL;DR

This paper measures the supermassive black hole in NGC 3258 using stellar dynamics and integral field spectroscopy, confirming previous gas-based measurements and demonstrating the reliability of both methods.

Contribution

First stellar dynamical mass measurement of the black hole in NGC 3258 using MUSE integral field spectroscopy and Schwarzschild modeling, validating gas dynamical results.

Findings

Black hole mass: (2.2 ± 0.2)×10^9 solar masses

Consistent with previous ALMA CO measurements

Supports reliability of stellar and gas dynamical methods

Abstract

We present a stellar dynamical mass measurement of the supermassive black hole in the elliptical (E1) galaxy NGC 3258. Our findings are based on integral field unit spectroscopy from the Multi Unit Spectroscopic Explorer (MUSE) observations in narrow-field mode with adaptive optics and the MUSE wide-field mode, from which we extract kinematic information by fitting the Ca II and Mg $b$ triplets, respectively. Using axisymmetric, three-integral Schwarzschild orbit library models, we fit the observed line-of-sight velocity distributions to infer the supermassive black hole mass, the $H$-band mass-to-light ratio, the asymptotic circular velocity, and the dark matter halo scale radius of the galaxy. We report a black hole mass of $(2.2 \pm 0.2)\times10^9 \ \rm M_{\scriptscriptstyle\odot}$ at an assumed distance of $31.9 \ \rm Mpc$. This value is in close agreement with a previous measurement from Atacama Large Millimeter/submillimeter Array CO observations. The consistency between these two measurements provides strong support for both the gas dynamical and stellar dynamical methods.