2017MNRAS.464..356V

We present spatially resolved two-dimensional stellar kinematics for the 41 most massive early-type galaxies (ETGs; M_K <= -25.7 mag, stellar mass M* >= 10^11.8 M_☉) of the volume-limited (D < 108 Mpc) MASSIVE survey. For each galaxy, we obtain high-quality spectra in the wavelength range of 3650-5850 Å from the 246-fibre Mitchell integral-field spectrograph at McDonald Observatory, covering a 107 arcsec x 107 arcsec field of view (often reaching 2 to 3 effective radii). We measure the 2D spatial distribution of each galaxy's angular momentum (λ and fast or slow rotator status), velocity dispersion (σ), and higher order non-Gaussian velocity features (Gauss-Hermite moments h₃ to h₆). Our sample contains a high fraction (∼80 per cent) of slow and non-rotators with λ <= 0.2. When combined with the lower mass ETGs in the ATLAS^3D survey, we find the fraction of slow rotators to increase dramatically with galaxy mass, reaching ∼50 per cent at M_K ∼ -25.5 mag and ∼90 per cent at M_K <= -26 mag. All of our fast rotators show a clear anticorrelation between h₃ and V/σ, and the slope of the anticorrelation is steeper in more round galaxies. The radial profiles of σ show a clear luminosity and environmental dependence: the 12 most luminous galaxies in our sample (M_K <= -26 mag) are all brightest cluster/group galaxies (except NGC 4874) and all have rising or nearly flat σ profiles, whereas five of the seven 'isolated' galaxies are all fainter than M_K = -25.8 mag and have falling σ. All of our galaxies have positive average h₄; the most luminous galaxies have average h₄ ∼ 0.05, while less luminous galaxies have a range of values between 0 and 0.05. Most of our galaxies show positive radial gradients in h₄, and those galaxies also tend to have rising σ profiles. We discuss the implications for the relationship among dynamical mass, σ, h₄, and velocity anisotropy for these massive galaxies.