New kinematic data and modeling efforts in the past few years have substantially expanded and revised dynamical measurements of black hole masses (M • ) at the centers of nearby galaxies. Here we compile an updated sample of 72 black holes and their host galaxies, and present revised scaling relations between M • and stellar velocity dispersion (σ), V -band luminosity (L), and bulge stellar mass (M bulge ), for different galaxy subsamples. Our best-fitting power law relations for the full galaxy sample are log 10 (M • ) = 8.32 + 5.64 log 10 (σ/200 km s −1 ), log 10 (M • ) = 9.23 + 1.11 log 10 (L/10 11 L ), and log 10 (M • ) = 8.46+1.05 log 10 (M bulge /10 11 M ). A log-quadratic fit to the M • −σ relation with an additional term of β 2 [log 10 (σ/200 km s −1 )] 2 gives β 2 = 1.68 ± 1.82 and does not decrease the intrinsic scatter in M • . Including 92 additional upper limits on M • does not change the slope of the M • − σ relation. When the early-and late-type galaxies are fit separately, we obtain similar slopes of 5.20 and 5.06 for the M • − σ relation but significantly different intercepts -M • in early-type galaxies are about 2 times higher than in late types at a given sigma. Within early-type galaxies, our fits to M • (σ) give M • that is about 2 times higher in galaxies with central core profiles than those with central powerlaw profiles. Our M • − L and M • − M bulge relations for early-type galaxies are similar to those from earlier compilations, and core and power-law galaxies yield similar L-and M bulge -based predictions for M • . When the conventional quadrature method is used to determine the intrinsic scatter in M • , our dataset shows weak evidence for increased scatter at M bulge < 10 11 M or L V < 10 10.3 L , while the scatter stays constant for 10 11 < M bulge < 10 12.3 M and 10 10.3 < L V < 10 11.5 L . A Bayesian analysis indicates that a larger sample of M • measurements would be needed to detect any statistically significant trend in the scatter with galaxy properties.

Observational work conducted over the past few decades indicates that all massive galaxies have supermassive black holes at their centres. Although the luminosities and brightness fluctuations of quasars in the early Universe suggest that some were powered by black holes with masses greater than 10 billion solar masses, the remnants of these objects have not been found in the nearby Universe. The giant elliptical galaxy Messier 87 hosts the hitherto most massive known black hole, which has a mass of 6.3 billion solar masses. Here we report that NGC 3842, the brightest galaxy in a cluster at a distance from Earth of 98 megaparsecs, has a central black hole with a mass of 9.7 billion solar masses, and that a black hole of comparable or greater mass is present in NGC 4889, the brightest galaxy in the Coma cluster (at a distance of 103 megaparsecs). These two black holes are significantly more massive than predicted by linearly extrapolating the widely used correlations between black-hole mass and the stellar velocity dispersion or bulge luminosity of the host galaxy. Although these correlations remain useful for predicting black-hole masses in less massive elliptical galaxies, our measurements suggest that different evolutionary processes influence the growth of the largest galaxies and their black holes.

Massive early-type galaxies represent the modern day remnants of the earliest major star formation episodes in the history of the universe. These galaxies are central to our understanding of the evolution of cosmic structure, stellar populations, and supermassive black holes, but the details of their complex formation histories remain uncertain. To address this situation, we have initiated the MASSIVE Survey, a volume-limited, multi-wavelength, integral-field spectroscopic (IFS) and photometric survey of the structure and dynamics of the ∼100 most massive early-type galaxies within a distance of 108 Mpc. This survey probes a stellar mass range M * 10 11.5 M and diverse galaxy environments that have not been systematically studied to date. Our wide-field IFS data cover about two effective radii of individual galaxies, and for a subset of them, we are acquiring additional IFS observations on sub-arcsecond scales with adaptive optics. We are also acquiring deep K-band imaging to trace the extended halos of the galaxies and measure accurate total magnitudes. Dynamical orbit modeling of the combined data will allow us to simultaneously determine the stellar, black hole, and dark matter halo masses. The primary goals of the project are to constrain the black hole scaling relations at high masses, investigate systematically the stellar initial mass function and dark matter distribution in massive galaxies, and probe the late-time assembly of ellipticals through stellar population and kinematical gradients. In this paper, we describe the MASSIVE sample selection, discuss the distinct demographics and structural and environmental properties of the selected galaxies, and provide an overview of our basic observational program, science goals and early survey results.

We examine stellar population gradients in ∼100 massive early-type galaxies spanning 180 * 370 s << km s −1 and M K of −22.5 to −26.5 mag, observed as part of the MASSIVE survey. Using integral-field spectroscopy from the Mitchell Spectrograph on the 2.7 m telescope at McDonald Observatory, we create stacked spectra as a function of radius for galaxies binned by their stellar velocity dispersion, stellar mass, and group richness. With excellent sampling at the highest stellar mass, we examine radial trends in stellar population properties extending to beyond twice the effective radius (R 2.5 ẽ). Specifically, we examine trends in age, metallicity, and abundance ratios of Mg, C, N, and Ca, and discuss the implications for star formation histories and elemental yields. At a fixed physical radius of 3-6 kpc (the likely size of the galaxy cores formed at high redshift), stellar age and [α/Fe] increase with increasing * s and depend only weakly on stellar mass, as we might expect if denser galaxies form their central cores earlier and faster. If we instead focus on R 1-1 .5 e , the trends in abundance and abundance ratio are washed out, as might be expected if the stars at large radius were accreted by smaller galaxies. Finally, we show that when controlling for * s , there are only very subtle differences in stellar population properties or gradients as a function of group richness; even at large radius, internal properties matter more than environment in determining star formation history.