WISDOM project – XXIII. Star-formation efficiencies of eight early-type galaxies and bulges observed with SITELLE and ALMA
Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 540:1 (2025) staf675
Abstract:
Early-type galaxies (ETGs) are known to harbour dense spheroids of stars with scarce star formation (SF). Approximately a quarter of these galaxies have rich molecular gas reservoirs yet do not form stars efficiently. These gas-rich ETGs have properties similar to those of bulges at the centres of spiral galaxies. We use spatially resolved observations (∼100 pc resolution) of warm ionized-gas emission lines (Hβ, [O iii], [N ii], H, and [S ii]) from the imaging Fourier transform spectrograph SITELLE at the Canada-France-Hawaii Telescope and cold molecular gas [12CO(2-1) or 12CO(3-2)] from the Atacama Large Millimeter/submillimeter Array to study the SF properties of eight ETGs and bulges. We use the ionized-gas emission lines to classify the ionization mechanisms and demonstrate a complete absence of regions dominated by SF ionization in these ETGs and bulges, despite abundant cold molecular gas. The ionization classifications also show that our ETGs and bulges are dominated by old stellar populations. We use the molecular gas surface densities and H -derived SF rates (in spiral galaxies outside of the bulges) or upper limits (in ETGs and bulges) to constrain the depletion times (inverse of the SF efficiencies), suggesting again suppressed SF in our ETGs and bulges. Finally, we use the molecular gas velocity fields to measure the gas kinematics, and show that bulge dynamics, particularly the strong shear due to the deep and steep gravitational potential wells, is an important SF regulation mechanism for at least half of our sample galaxies.WISDOM Project – XXII. A 5 per cent precision CO-dynamical supermassive black hole mass measurement in the galaxy NGC 383
Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 537:1 (2025) 520-536
Abstract:
<jats:title>ABSTRACT</jats:title> <jats:p>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 $^{12}$CO(2-1) emission line with an angular resolution of $0.050{\,\rm arcsec}\times 0.024{\,\rm arcsec}$ ($\approx 16\times 8$ pc$^2$). These observations spatially resolve the nuclear molecular gas disc down to $\approx 41\,300$ Schwarzschild radii and the SMBH sphere of influence by a factor of $\approx 24$ 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 $\approx 1040$ 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 $\approx 0.3\,{\rm arcsec}$. By forward modelling the mass distribution and ALMA data cube, we infer an SMBH mass of $(3.58\pm 0.19)\times 10^9$ M$_\odot$ ($1\sigma$ confidence interval), more precise (5 per cent) but consistent within $\approx 1.4\sigma$ with the previous measurement using lower resolution molecular gas data. Our measurement emphasizes the importance of high spatial resolution observations for precise SMBH mass determinations.</jats:p>WISDOM Project -- XXII. A 5% precision CO-dynamical supermassive black hole mass measurement in the galaxy NGC 383
(2025)
WISDOM Project -- XIX. Figures of merit for supermassive black hole mass measurements using molecular gas and/or megamaser kinematics
(2024)
WISDOM Project – XIX. Figures of merit for supermassive black hole mass measurements using molecular gas and/or megamaser kinematics
Monthly Notices of the Royal Astronomical Society Oxford University Press 530:3 (2024) 3240-3251