Measurements Of Stellar Kinematics Research Articles

A Relationship between Nuclear Black Hole Mass and Galaxy Velocity Dispersion

We describe a correlation between the mass Mbh of a galaxy's central black hole and the luminosity-weighted line-of-sight velocity dispersion σe within the half-light radius. The result is based on a sample of 26 galaxies, including 13 galaxies with new determinations of black hole masses from Hubble Space Telescope measurements of stellar kinematics. The best-fit correlation is Mbh = 1.2(±0.2) × 108 M☉(σe/200 km s-1)3.75 (±0.3) over almost 3 orders of magnitude in Mbh; the scatter in Mbh at fixed σe is only 0.30 dex, and most of this is due to observational errors. The Mbh-σe relation is of interest not only for its strong predictive power but also because it implies that central black hole mass is constrained by and closely related to properties of the host galaxy's bulge.

Kinematics of early-type galaxies in compact groups: HCG 67, HCG 74 and HCG 79

AbstractWe present measurements of stellar kinematics for seven early-type galaxies in HCG 67, HCG 74 and HCG 79. These data are aimed at studying the relation between the environment and the dynamics, structure and stellar content of early-type galaxies. In the present three groups, the kinematic features we observed cannot be associated unambiguously to physical interactions. Visible morphological peculiarities do not appear correlated with kinematical perturbations.

Kinematics of early-type galaxies in compact groups

We present measurements of stellar kinematics for seven early-type galaxies in HCG 67, HCG 74, and HCG 79. These data are aimed at studying the relation between the environment and the dynamics, structure and stellar content of early-type galaxies. In the present three groups, the kinematic features we observed cannot be as- sociated unambiguously to physical interactions. Visible morphological peculiarities do not appear correlated with kinematical perturbations.

New measurements of stellar kinematics in the core of M87

We present new, high signal-to-noise ratio spectra of the core of M87. These data confirm Dressler's claim that the velocity dispersion does not continue to rise within r = 1 arcsec, but levels off at {simga} ~ 360 km s^-1^. The line strength of the Mg b feature falls sharply in the nucleus due to the contribution of a nonthermal spectrum. The central light spike in M87 is completely explained by this non-thermal component, in contradiction to Dressler's (1980) claim that much of the spike is due to a central star cluster. Maximum entropy models have been constructed to match the new data. They exclude the possibility of a supermassive black hole M > 4 x 10^9^ M_sun_ unless a highly contrived model is accepted. A model with no supermassive black hole which has a mild anisotropy in the stellar orbits is a good fit to the data, but a model having only slightly greater anisotropy can accommodate a central mass concentration of up to 10^9^ M_sun_.