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Abstract We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 2 observations of CO(2–1) emission from the circumnuclear disks in two early-type galaxies, NGC 1380 and NGC 6861. The disk in each galaxy is highly inclined (i∼ 75°), and the projected velocities of the molecular gas near the galaxy centers are ∼300 km s−1in NGC 1380 and ∼500 km s−1in NGC 6861. We fit thin disk dynamical models to the ALMA data cubes to constrain the masses of the central black holes (BHs). We created host galaxy models using Hubble Space Telescope images for the extended stellar mass distributions and incorporated a range of plausible central dust extinction values. For NGC 1380, our best-fit model yieldsMBH= 1.47 × 108M⊙with a ∼40% uncertainty. For NGC 6861, the lack of dynamical tracers within the BH’s sphere of influence due to a central hole in the gas distribution precludes a precise measurement ofMBH. However, our model fits require a value forMBHin the range of (1–3) × 109M⊙in NGC 6861 to reproduce the observations. The BH masses are generally consistent with predictions from local BH–host galaxy scaling relations. Systematic uncertainties associated with dust extinction of the host galaxy light and choice of host galaxy mass model dominate the error budget of both measurements. Despite these limitations, the measurements demonstrate ALMA’s ability to provide constraints on BH masses in cases where the BH’s projected radius of influence is marginally resolved or the gas distribution has a central hole.
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The Mass of the Black Hole in NGC 5273 from Stellar Dynamical Modeling
Abstract We present a new constraint on the mass of the black hole in the active S0 galaxy NGC 5273. Due to the proximity of the galaxy at 16.6 ± 2.1 Mpc, we were able to resolve and extract the bulk motions of stars near the central black hole using adaptive-optics-assisted observations with the Gemini Near-infrared Integral Field Spectrograph, as well as constrain the large-scale kinematics using archival Spectroscopic Areal Unit for Research and Optical Nebulae spectroscopy. High-resolution Hubble Space Telescope imaging allowed us to generate a surface-brightness decomposition, determine approximate mass-to-light ratios for the bulge and disk, and obtain an estimate for the disk inclination. We constructed an extensive library of dynamical models using the Schwarzschild orbit-superposition code FORSTAND, exploring a range of disk and bulge shapes, halo masses, etc. We determined a black hole mass ofM•= [0.5–2] × 107M⊙, where the low side of the range is in agreement with the reverberation mapping measurement ofM•= [4.7 ± 1.6] × 106M⊙. NGC 5273 is one of the few nearby galaxies that hosts a broad-lined active galactic nucleus, allowing a crucial comparison of black hole masses derived from independent mass-measurement techniques.
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- PAR ID:
- 10415065
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 949
- Issue:
- 1
- ISSN:
- 0004-637X
- Format(s):
- Medium: X Size: Article No. 13
- Size(s):
- Article No. 13
- Sponsoring Org:
- National Science Foundation
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