SIMBAD references

2015ApJ...804L..21C - Astrophys. J., 804, L21 (2015/May-1)

Small scatter and nearly isothermal mass profiles to four half-light radii from two-dimensional stellar dynamics of early-type galaxies.

CAPPELLARI M., ROMANOWSKY A.J., BRODIE J.P., FORBES D.A., STRADER J., FOSTER C., KARTHA S.S., PASTORELLO N., POTA V., SPITLER L.R., USHER C. and ARNOLD J.A.

Abstract (from CDS):

We study the total mass-density profile for a sample of 14 fast-rotator early-type galaxies (stellar masses 10.2 ≲ logM*/M{sun= ≲ 11.7). We combine observations from the SLUGGS and ATLAS3D surveys to map out the stellar kinematics in two dimensions, out to a median radius for the sample of four half-light radii Re(or 10 kpc) and a maximum radius of 2.0-6.2 Re(or 4-21 kpc). We use axisymmetric dynamical models based on the Jeans equations, which allow for a spatially varying anisotropy; employ quite general profiles for the dark halos; and, in particular, do not place any restrictions on the profile slope. This is made possible by the availability of spatially extended two-dimensional kinematics. We find that our relatively simple models provide a remarkably good description of the observed kinematics. The resulting total density profiles are well described by a nearly isothermal power law ρtot(r) ∝ r–γ from Re/10 to at least 4Re, the largest average deviation being 11%. The average logarithmic slope is <γ> = 2.19 ± 0.03 with observed rms scatter of just σγ = 0.11. This scatter out to large radii, where dark matter dominates, is as small as previously reported by lensing studies around r ≈ Re/2, where the stars dominate. Our bulge-halo conspiracy places much tighter constraints on galaxy formation models. It illustrates the power of two-dimensional stellar kinematics observations at large radii. It is now important to test the generality of our results for different galaxy types and larger samples.

Abstract Copyright:

Journal keyword(s): galaxies: elliptical and lenticular, cD - galaxies: formation - galaxies: kinematics and dynamics - galaxies: structure

Simbad objects: 14

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