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Abstract:
We use observations from the GEMINI-N/GMOS integral field spectrograph (IFS) to obtain spatially resolved stellar kinematics of the central ~1 kpc of 20 early-type galaxies (ETGs) with stellar masses greater than 1011.7 M ⊙ in the MASSIVE survey. Together with observations from the wide-field Mitchell IFS at McDonald Observatory in our earlier work, we obtain unprecedentedly detailed kinematic maps of local massive ETGs, covering a scale of ~0.1–30 kpc. The high (~120) signal-to-noise ratio of the GMOS spectra enables us to obtain two-dimensional maps of the line-of-sight velocity and velocity dispersion σ, as well as the skewness h 3 and kurtosis h 4 of the stellar velocity distributions. All but one galaxy in the sample have σ(R) profiles that increase toward the center, whereas the slope of σ(R) at one effective radius (R e ) can be of either sign. The h 4 is generally positive, with 14 of the 20 galaxies having positive h 4 within the GMOS aperture and 18 having positive h 4 within 1R e . The positive h 4 and rising σ(R) toward small radii are indicative of a central black hole and velocity anisotropy. We demonstrate the constraining power of the data on the mass distributions in ETGs by applying Jeans anisotropic modeling (JAM) to NGC 1453, the most regular fast rotator in the sample. Despite the limitations of JAM, we obtain a clear χ 2 minimum in black hole mass, stellar mass-to-light ratio, velocity anisotropy parameters, and circular velocity of the dark matter halo.
