My work on SMBHs takes up most of my life right now. The work I do in this area is predominately related to stuff I do with the Nuker collaboration (PI Doug Richstone).

Studies of elliptical galaxies and spiral bulges have led to the discoveries that most or all hot galaxies contain massive dark objects at their centers, presumably black holes; and that there is a remarkably tight correlation between the black hole mass and the luminosity-weighted velocity dispersion of the hot component of the galaxy. This M–σ relation suggests a strong link between black hole formation, galaxy formation, and active galactic nuclei (AGNs); and once it is understood, this link should advance our understanding of all three processes.

Gültekin, K. et al. (2009b), The M–σ and M–L Relations in Galactic Bulges, and Determinations of Their Intrinsic Scatter ApJ, 698, 198.

We derive improved versions of the relations between supermassive black hole mass (M_BH) and host-galaxy bulge velocity dispersion (σ) and luminosity (L; the M–σ and M–L relations), based on 49 M_BH measurements and 19 upper limits. Particular attention is paid to recovery of the intrinsic scatter (ε₀) in both relations. We find log(M_BH / M_⊙) = α + β * log(σ / 200 km/s) with (α, β, ε₀) = (8.12 ± 0.08, 4.24 ± 0.41, 0.44 ± 0.06) for all galaxies and (α, β, ε₀) = (8.23 ± 0.08, 3.96 ± 0.42, 0.31 ± 0.06) for ellipticals. The results for ellipticals are consistent with previous studies, but the intrinsic scatter recovered for spirals is significantly larger. The scatter inferred reinforces the need for its consideration when calculating local black hole mass function based on the M-sigma relation, and further implies that there may be substantial selection bias in studies of the evolution of the M–σ relation. We estimate the M–L relationship as log(M_BH / M_⊙) = α + β * log(L_V / 10¹¹ L_⊙,V) of (α, β, ε₀) = (8.95 ± 0.11, 1.11 ± 0.18, 0.38 ± 0.09); using only early-type galaxies. These results appear to be insensitive to a wide range of assumptions about the measurement errors and the distribution of intrinsic scatter. We show that culling the sample according to the resolution of the black hole’s sphere of influence biases the relations to larger mean masses, larger slopes, and incorrect intrinsic residuals.

The M–σ relation for galaxies with dynamical measurements. The symbol indicates the method of BH mass measurement: stellar dynamical (pentagrams), gas dynamical (circles), masers (asterisks). Arrows indicate 3σ₆₈ upper limits to BH mass. If the 3σ₆₈ limit is not available, we plot it at 3 times the 1σ₆₈ or at 1.5 times the 2σ₆₈ limits. For clarity, we only plot error boxes for upper limits that are close to or below the best-fit relation. The color of the error ellipse indicates the Hubble type of the host galaxy: elliptical (red), S0 (green), and spiral (blue). The saturation of the colors in the error ellipses or boxes is inversely proportional to the area of the ellipse or box. Squares are galaxies that we do not include in our fit. The line is the best fit relation to the full sample: M_BH = 10^8.12 M_⊙(σ / 200 km/s)^4.24. The mass uncertainty for NGC 4258 has been plotted much larger than its actual value so that it will show on this plot. For clarity, we omit labels of some galaxies in crowded regions.

Gültekin, K. et al. (2009a), A Quintet of Black Hole Mass Determinations ApJ, 695, 1577.

We report five new measurements of central black hole masses based on Space Telescope Imaging Spectrograph (STIS) and Wide Field Planetary Camera 2 (WFPC2) observations with the Hubble Space Telescope (HST) and on axisymmetric, three-integral, Schwarzschild orbit-library kinematic models. We selected a sample of galaxies within a narrow range in velocity dispersion that cover a range of galaxy parameters (including Hubble type and core/power-law surface density profile) where we expected to be able to resolve the galaxy’s sphere of influence based on the predicted value of the black hole mass from the M–σ relation. We find masses for the following galaxies:

all significantly excluding M_BH = 0. For

which is significantly below predictions from M–σ and M–L relations and consistent with M_BH = 0, though the presence of a double bar in this galaxy may present problems for our axisymmetric code.

Gauss–Hermite moments of line-of-sight velocity distributions (LOSVDs) for NGC 4026 for HST STIS data (blue crosses), ground-based data long the major axis (red diamonds) and minor axis (green triangles). Ground-based data are from Fisher (1997), for which the h₃ and h₄ moments have been interpolated. Because of the interpolation, the scatter in the data is less than the error bars. The LOSVDs show a sharp increase in velocity dispersion toward the center. The jagged black lines (solid for major axis, dashed for minor axis) are from the best-fit model, which has M_BH = 2.2 × 10⁸ M_⊙ and Υ = 4.6. The best-fit model without a black hole (red dotted line) has Υ = 5.6.