The MASSIVE survey – VIII. Stellar velocity dispersion profiles and environmental dependence of early-type galaxies

Abstract

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 M K < −25.3 mag, or stellar mass M * > ∼ 4 × 10 11 M , 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 inner and γ outer of σ(R). While γ inner is mostly negative, of the 56 galaxies with sufficient radial coverage to determine γ 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 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 h 4 . 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.

A 40 Billion Solar-mass Black Hole in the Extreme Core of Holm 15A, the Central Galaxy of Abell 85

“…To better understand Holm 15A's place among other known massive ETGs we will compare it's stellar kinematics to ETGs from the MASSIVE survey (Ma et al 2014, and subsequent MASSIVE survey papers). Characterizing Holm15 A's velocity dispersion profile, σ(r) (see Section 3.2) by fitting a combined power-law profile as suggested by Veale et al (2018) in their study of the 90 ETGs of the MASSIVE survey, we find an inner logarithmic slope γ inner = −0.017 ± 0.007 of the σ profile at ∼ 2 kpc and an outer logarithmic slope γ outer = 0.029 ± 0.009 at ∼ 20 kpc. Roughly 90% of BCGs in the MASSIVE survey have γ inner ≤ 0 and ∼ 60% with γ outer ≥ 0.…”

Spatially Resolved Stellar Populations and Kinematics with KCWI: Probing the Assembly History of the Massive Early-type Galaxy NGC 1407

“…Although NGC 1407 was not included in that survey, it would lie at the lower mass limit (log(M * /M ⊙ ) > 11.6) of their sample. Veale et al (2018) found that around ∼15% of the MASSIVE galaxies presented this rising profile (see also ?). However, Veale et al (2018) also found that massive galaxies with such a rising σ profiles also have increasing values of the 4th Gauss-Hermite coefficient (h 4 ) with radius.…”

“…Veale et al (2018) found that around ∼15% of the MASSIVE galaxies presented this rising profile (see also ?). However, Veale et al (2018) also found that massive galaxies with such a rising σ profiles also have increasing values of the 4th Gauss-Hermite coefficient (h 4 ) with radius. As shown in Figure 4, the 2D map of NGC 1407's h 4 and its radial gradients show this increase up to ∼0.6R e (also reported in J+18).…”

The MASSIVE Survey. XV. A Stellar Dynamical Mass Measurement of the Supermassive Black Hole in Massive Elliptical Galaxy NGC 1453

“…We have obtained comprehensive spectroscopic data using IFS on both sub-arcsecond and arc-minute scales and performed uniform measurements of the spatiallyresolved kinematics. Many results on the stellar kinematics and stellar populations of MASSIVE galaxies out to a few effective radii from our wide-field IFS observations can be found in Veale et al (2017bVeale et al ( ,a, 2018; Ene et al (2018); Greene et al (2015Greene et al ( , 2019. Results from finely-resolved stellar kinematics in the central ∼ 2 kpc regions of 20 MASSIVE galaxies are presented in Ene et al (2019); Ene et al (2020).…”