Circumnuclear Dust in Luminous Early-Type Galaxies -- I. Sample Properties and Stellar Luminosity Models

TL;DR

This study presents new optical and near-IR imaging of 26 luminous early-type galaxies with circumnuclear dust disks, improving stellar luminosity models and aiding black hole mass measurements to refine galaxy scaling relations.

Contribution

The paper provides high-resolution HST images and detailed stellar luminosity models for a sample of ETGs, enhancing black hole mass estimates and understanding of circumnuclear dust properties.

Findings

CNDs are generally optically thick in near-IR ($A_H vert extgreater 1$ mag)

Most CNDs align with larger stellar axes, with some exceptions

Dust impact on MGE significantly affects black hole mass uncertainties

Abstract

Dusty circumnuclear disks (CNDs) in luminous early-type galaxies (ETGs) show regular, dynamically cold molecular gas kinematics. For a growing number of ETGs, Atacama Large Millimeter/sub-millimeter Array (ALMA) CO imaging and detailed gas-dynamical modeling facilitate moderate-to-high precision black hole (BH) mass ($M_{BH}$) determinations. From the ALMA archive, we identified a subset of 26 ETGs with estimated $M_{BH}/M_{\odot} \gtrsim 10^8$ to a few $\times$10$^9$ and clean CO kinematics but that previously did not have sufficiently high angular resolution near-IR observations to mitigate dust obscuration when constructing stellar luminosity models. We present new optical and near-IR Hubble Space Telescope (HST) images of this sample to supplement the archival HST data, detailing the sample properties and data analysis techniques. After masking the most apparent dust features, we measure stellar surface brightness profiles and model the luminosities using the multi-Gaussian expansion (MGE) formalism. Some of these MGEs have already been used in CO dynamical modeling efforts to secure quality \mbh\ determinations, and the remaining ETG targets here are expected to significantly improve the high-mass end of the current BH census, facilitating new scrutiny of local BH mass-host galaxy scaling relationships. We also explore stellar isophotal behavior and general dust properties, finding these CNDs generally become optically thick in the near-IR ($A_H \gtrsim 1$ mag). These CNDs are typically well-aligned with the larger-scale stellar photometric axes with a few notable exceptions. Uncertain dust impact on the MGE often dominates the BH mass error budget, so extensions of this work will focus on constraining CND dust attenuation.