WISDOM Project II: Molecular gas measurement of the supermassive black hole mass in NGC4697

Davis, Timothy A. ORCID: https://orcid.org/0000-0003-4932-9379, Bureau, Martin, Onishi, Kyoko, Cappellari, Michele, Iguchi, Saturo and Sarzi, March 2017. WISDOM Project II: Molecular gas measurement of the supermassive black hole mass in NGC4697. Monthly Notices of the Royal Astronomical Society 458 (4) , pp. 4675-4690. 10.1093/mnras/stw3217

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Abstract

As part of the mm-Wave Interferometric Survey of Dark Object Masses (WISDOM) project, we present an estimate of the mass of the supermassive black hole (SMBH) in the nearby fast-rotating early-type galaxy NGC 4697. This estimate is based on Atacama Large Millimeter/submillimeter Array (ALMA) cycle-3 observations of the 12CO(2–1) emission line with a linear resolution of 29 pc (0.53 arcsec). We find that NGC 4697 hosts a small relaxed central molecular gas disc with a mass of 1.6 × 107 M⊙, co-spatial with the obscuring dust disc visible in optical Hubble Space Telescope imaging. We also resolve thermal 1 mm continuum emission from the dust in this disc. NGC 4697 is found to have a very low molecular gas velocity dispersion, σgas = 1.65 +0.68−0.65 −0.65+0.68 km s−1. This seems to be partially because the giant molecular cloud mass function is not fully sampled, but other mechanisms such as chemical differentiation in a hard radiation field or morphological quenching also seem to be required. We detect a Keplerian increase of the rotation of the molecular gas in the very centre of NGC 4697, and use forward modelling of the ALMA data cube in a Bayesian framework with the KINematic Molecular Simulation (KINMS) code to estimate an SMBH mass of (1.3 +0.18−0.17 −0.17+0.18 ) × 108 M⊙ and an i-band mass-to-light ratio of 2.14 +0.04−0.05 −0.05+0.04 M⊙/L⊙ (at the 99 per cent confidence level). Our estimate of the SMBH mass is entirely consistent with previous measurements from stellar kinematics. This increases confidence in the growing number of SMBH mass estimates being obtained in the ALMA era.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Subjects:	Q Science > QB Astronomy
Publisher:	Oxford University Press
ISSN:	0035-8711
Funders:	Science and Technology Facilites Council (STFC)
Date of First Compliant Deposit:	10 January 2017
Date of Acceptance:	7 December 2016
Last Modified:	15 Nov 2024 16:45
URI:	https://orca.cardiff.ac.uk/id/eprint/97312

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