2017/08/31 by Melanie Veale, Chung‐Pei Ma, Chung-Pei Ma +5 · 2 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #Galaxy #Halo #Physics #RADIUS #Sigma #Star formation #Stellar mass #Velocity dispersion #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.1093/mnras/stx2717
Accepted/in press, MNRAS
openalex publication_date 2017/10/18 · arxiv created 2017/10/24 · arxiv updated 2017/12/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We measure the radial profiles of the stellar velocity dispersions, σ(R), for 90 early-type galaxies (ETGs) in the MASSIVE survey, a volume-limited integral-field spectroscopic (IFS) galaxy survey targeting all northern-sky ETGs with absolute K-band magnitude MK < -25.3 mag, or stellar mass M_* > 4 × 1011 M_\odot, within 108 Mpc. Our wide-field 107" × 107" IFS data cover radii as large as 40 kpc, for which we quantify separately the inner (2 kpc) and outer (20 kpc) logarithmic slopes γ\rm inner and γ\rm outer of σ(R). While γ\rm inner is mostly negative, of the 56 galaxies with sufficient radial coverage to determine γ\rm outer we find 36% to have rising outer dispersion profiles, 30% to be flat within the uncertainties, and 34% to be falling. The fraction of galaxies with rising outer profiles increases with M_* and in denser galaxy environment, with 10 of the 11 most massive galaxies in our sample having flat or rising dispersion profiles. The strongest environmental correlations are with local density and halo mass, but a weaker correlation with large-scale density also exists. The average γ\rm outer is similar for brightest group galaxies, satellites, and isolated galaxies in our sample. We find a clear positive correlation between the gradients of the outer dispersion profile and the gradients of the velocity kurtosis h4. Altogether, our kinematic results suggest that the increasing fraction of rising dispersion profiles in the most massive ETGs are caused (at least in part) by variations in the total mass profiles rather than in the velocity anisotropy alone.