WISDOM Project – XXII. A 5 % precision CO-dynamical supermassive black hole mass measurement in the galaxy NGC 383

Zhang, Hengyue, Bureau, Martin, Ruffa, Ilaria, Cappellari, Michele, Davis, Timothy A ORCID: https://orcid.org/0000-0003-4932-9379, Dominiak, Pandora, Elford, Jacob S, Iguchi, Satoru, Lelli, Federico, Sarzi, Marc and Williams, Thomas G 2025. WISDOM Project – XXII. A 5 % precision CO-dynamical supermassive black hole mass measurement in the galaxy NGC 383. Monthly Notices of the Royal Astronomical Society 537 (1) , pp. 520-536. 10.1093/mnras/staf055

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Abstract

We present a measurement of the supermassive black hole (SMBH) mass of the nearby lenticular galaxy NGC 383, based on Atacama Large Millimeter/sub-millimeter Array (ALMA) observations of the 12CO(2-1) emission line with an angular resolution of $0\hbox{$.\!\!^{\prime \prime }$}050\times 0\hbox{$.\!\!^{\prime \prime }$}024$ (≈16 × 8 pc2). These observations spatially resolve the nuclear molecular gas disc down to ≈41, 300 Schwarzschild radii and the SMBH sphere of influence by a factor of ≈24 radially, better than any other SMBH mass measurement using molecular gas to date. The high resolution enables us to probe material with a maximum circular velocity of ≈1040 km s−1, even higher than those of the highest-resolution SMBH mass measurements using megamasers. We detect a clear Keplerian increase (from the outside in) of the line-of-sight rotation velocities, a slight offset between the gas disc kinematic (i.e. the position of the SMBH) and morphological (i.e. the centre of the molecular gas emission) centres, an asymmetry of the innermost rotation velocity peaks and evidence for a mild position angle warp and/or non-circular motions within the central $\approx 0\hbox{$.\!\!^{\prime \prime }$}3$. By forward modelling the mass distribution and ALMA data cube, we infer a SMBH mass of (3.58 ± 0.19) × 109 M⊙ (1σ confidence interval), more precise (5%) but consistent within ≈1.4σ with the previous measurement using lower-resolution molecular gas data. Our measurement emphasises the importance of high spatial resolution observations for precise SMBH mass determinations.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Additional Information:	License information from Publisher: LICENSE 1: URL: https://creativecommons.org/licenses/by/4.0/, Start Date: 2025-01-12
Publisher:	Oxford University Press
ISSN:	0035-8711
Date of First Compliant Deposit:	27 January 2025
Date of Acceptance:	8 January 2025
Last Modified:	27 Jan 2025 16:45
URI:	https://orca.cardiff.ac.uk/id/eprint/175643

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