We present a dynamical-mass measurement of the supermassive black hole (SMBH) in the nearby double-barred spiral galaxy NGC 3504 as part of the Measuring Black Holes in Below Milky Way (M ⋆) mass galaxies (MBHBM ⋆) Project. Our analysis is based on Atacama Large Millimeter/submillimeter Array (ALMA) Cycle-5 observations of the 12 CO(2 − 1) emission line. These observations probe NGC 3504's circumnuclear gas disk (CND). Our dynamical model of the CND simultaneously constrains a black hole (BH) mass of 1.6 +0.6 −0.4 × 10 7 M ⊙ , which is consistent with the empirical BH-galaxy scaling relations, and a mass-to-light ratio in H-band of 0.44 ± 0.12 (M ⊙ /L ⊙). This measurement also relies on our new distant estimation to the galaxy of 32.4 ± 2.1 Mpc using the surface brightness fluctuation method (SBF), which is much further than the existing distant estimates. Additionally, our observations detect a central deficit in the 12 CO(2 − 1) integrated intensity map with a diameter of 6.3 pc at the putative position of the SMBH. However, we find a dense gas tracer CS(5 − 4) peaks at the galaxy center, filling in the 12 CO(2 − 1)-attenuated hole. Holes like this one are observed in other galaxies, and our observations suggest these may be caused by changing excitation conditions rather than a true absence of molecular gas around the nucleus.

Different massive black hole mass -host galaxy scaling relations suggest that the growth of massive black holes is entangled with the evolution of their host galaxies. The number of measured black hole masses is still limited, and additional measurements are necessary to understand the underlying physics of this apparent co-evolution. We add six new black hole mass (M BH ) measurements of nearby fast rotating early-type galaxies to the known black hole mass sample, namely NGC 584, NGC 2784, NGC 3640, NGC 4570, NGC 4281 and NGC 7049. Our target galaxies have effective velocity dispersions (σ e ) between 170 and 245 km s −1 , and thus this work provides additional insight into the black hole properties of intermediate-mass early-type galaxies. We combine high-resolution adaptive-optics SINFONI data with large-scale MUSE, VIMOS and SAURON data from ATLAS 3D to derive two-dimensional stellar kinematics maps. We then build both Jeans Anisotropic Models and axisymmetric Schwarzschild models to measure the central black hole masses. Our Schwarzschild models provide black hole masses of (1.3 ± 0.5) × 10 8 M for NGC 584, (1.0 ± 0.6) × 10 8 M for NGC 2784, (7.7 ± 5) × 10 7 M for NGC 3640, (5.4 ± 0.8) × 10 8 M for NGC 4281, (6.8 ± 2.0) × 10 7 M for NGC 4570 and (3.2 ± 0.8) × 10 8 M for NGC 7049 at 3σ confidence level, which are consistent with recent M BH -σ e scaling relations. NGC 3640 has a velocity dispersion dip and NGC 7049 a constant velocity dispersion in the center, but we can clearly constrain their lower black hole mass limit. We conclude our analysis with a test on NGC 4570 taking into account a variable mass-to-light ratio (M/L) when constructing dynamical models. When considering M/L variations linked mostly to radial changes in the stellar metallicity, we find that the dynamically determined black hole mass from NGC 4570 decreases by 30%. Further investigations are needed in the future to account for the impact of radial M/L gradients on dynamical modeling.

We present mass estimates of supermassive black holes in six nearby fast rotating early-type galaxies (NGC 4339, NGC 4434, NGC 4474, NGC 4551, NGC 4578 and NGC 4762) with effective stellar velocity dispersion around 100 km/s. We use near-infrared laser-guide adaptive optics observations with the GEMINI/NIFS to derive stellar kinematics in the galactic nuclei, and SAURON observations from the ATLAS 3D Survey for large-scale kinematics. We build axisymmetric Jeans Anisotropic Models and axisymmetric Schwarzschild dynamical models. Both modelling approaches recover consistent orbital anisotropies and black hole masses within 1 − 2σ confidence level, except for one galaxy for which the difference is just above the 3σ level. Two black holes (NGC 4339 and NGC 4434) are amongst the largest outliers from the current black hole mass -velocity dispersion relation, with masses of (4.3 +4.8 −2.3 ) × 10 7 and (7.0 +2.0 −2.8 ) × 10 7 M , respectively (3σ confidence level). The black holes in NGC 4578 and NGC 4762 lie on the scaling relation with masses of (1.9 +0.6 −1.4 ) × 10 7 and (2.3 +0.9 −0.6 ) × 10 7 M , respectively (3σ confidence level). For two galaxies (NGC 4474 and NGC 4551) we are able to place upper limits on their black holes masses (< 7×10 6 and < 5×10 6 M , respectively, 3σ confidence level). The kinematics for these galaxies clearly indicate central velocity dispersion drops within a radius of 35 pc and 80 pc, respectively. These drops cannot be associated with cold stellar structures and our data do not have the resolution to exclude black holes with masses an order of magnitude smaller than the predictions. Parametrizing the orbital distribution in spherical coordinates, the vicinity of the black holes is characterized by isotropic or mildly tangential anisotropy.

We present our mass estimate of the central black hole in the isolated spiral galaxy NGC 4414. Using natural guide star adaptive optics assisted observations with the Gemini Near-Infrared Integral Field Spectrometer (NIFS) and the natural seeing Gemini MultiObject Spectrographs-North (GMOS), we derived two-dimensional stellar kinematic maps of NGC 4414 covering the central 1.5 arcsec and 10 arcsec, respectively, at a NIFS spatial resolution of 0.13 arcsec. The kinematic maps reveal a regular rotation pattern and a central velocity dispersion dip down to around 105 km/s. We constructed dynamical models using two different methods: Jeans anisotropic dynamical modeling and axisymmetric Schwarzschild modeling. Both modeling methods give consistent results, but we cannot constrain the lower mass limit and only measure an upper limit for the black hole mass of M BH = 1.56 × 10 6 M (at 3 σ level) which is at least 1σ below the recent M BH − σ e relations. Further tests with dark matter, mass-to-light ratio variation and different light models confirm that our results are not dominated by uncertainties. The derived upper limit mass is not only below the M BH − σ e relation, but is also five times lower than the lower limit black hole mass anticipated from the resolution limit of the sphere of influence. This proves that via high quality integral field data we are now able to push black hole measurements down to at least five times less than the resolution limit.