The MASSIVE Survey – V. Spatially resolved stellar angular momentum, velocity dispersion, and higher moments of the 41 most massive local early-type galaxies
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© 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. We present spatially resolved two-dimensional stellar kinematics for the 41 most massive early-type galaxies (ETGs; MK ≲ -25.7 mag, stellar mass M* ≳ 1011.8 M⊙) of the volumelimited (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×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 ATLAS3D survey, we find the fraction of slow rotators to increase dramatically with galaxy mass, reaching ~50 per cent at MK ~ -25.5 mag and ~90 per cent at MK ≲ -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 s show a clear luminosity and environmental dependence: the 12 most luminous galaxies in our sample (MK ≲ -26 mag) are all brightest cluster/group galaxies (except NGC 4874) and all have rising or nearly flat s profiles, whereas five of the seven 'isolated' galaxies are all fainter than MK = -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 s profiles. We discuss the implications for the relationship among dynamical mass, σ, h4, and velocity anisotropy for these massive galaxies.
author list (cited authors)
Veale, M., Ma, C., Thomas, J., Greene, J. E., McConnell, N. J., Walsh, J., ... Janish, R.