Black hole mass measurements using ionized gas discs: systematic dust effects

TL;DR

This study uses simulations to show that interstellar dust causes a slight underestimation of supermassive black hole masses derived from ionized gas disc rotation curves, highlighting the need to account for dust effects.

Contribution

The paper demonstrates through simulations that dust attenuation systematically biases black hole mass measurements from ionized gas kinematics.

Findings

Dust causes a 10-20% underestimation of black hole masses.

Rotation curve shapes are minimally affected by dust.

Systematic dust effects should be considered in SMBH mass estimates.

Abstract

Using detailed Monte Carlo radiative transfer simulations in realistic models for galactic nuclei, we investigate the influence of interstellar dust in ionized gas discs on the rotation curves and the resulting black hole mass measurements. We find that absorption and scattering by interstellar dust leaves the shape of the rotation curves basically unaltered, but slightly decreases the central slope of the rotation curves. As a result, the "observed" black hole masses are systematically underestimated by some 10 to 20% for realistic optical depths. We therefore argue that the systematic effect of dust attenuation should be taken into account when estimating SMBH masses using ionized gas kinematics.