The Structure and Dynamics of Massive Early-Type Galaxies: On Homology, Isothermality, and Isotropy Inside One Effective Radius - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue The Astrophysical journal letters Année : 2009

The Structure and Dynamics of Massive Early-Type Galaxies: On Homology, Isothermality, and Isotropy Inside One Effective Radius

L. V. E. Koopmans
  • Fonction : Auteur
A. Bolton
  • Fonction : Auteur
T. Treu
  • Fonction : Auteur
O. Czoske
  • Fonction : Auteur
M. W. Auger
  • Fonction : Auteur
M. Barnabè
  • Fonction : Auteur
S. Vegetti
  • Fonction : Auteur
L. A. Moustakas
  • Fonction : Auteur
S. Burles
  • Fonction : Auteur

Résumé

Based on 58 SLACS strong-lens early-type galaxies (ETGs) with direct total-mass and stellar-velocity dispersion measurements, we find that inside one effective radius massive elliptical galaxies with M eff gsim 3 × 1010 M sun are well approximated by a power-law ellipsoid, with an average logarithmic density slope of langγ'LDrang ≡ -dlog(ρtot)/dlog(r) = 2.085+0.025 -0.018 (random error on mean) for isotropic orbits with β r = 0, ±0.1 (syst.) and σ_{γ'} ≲ 0.20^{+0.04}_{-0.02} intrinsic scatter (all errors indicate the 68% CL). We find no correlation of γ'LD with galaxy mass (M eff), rescaled radius (i.e., R einst/R eff) or redshift, despite intrinsic differences in density-slope between galaxies. Based on scaling relations, the average logarithmic density slope can be derived in an alternative manner, fully independent from dynamics, yielding langγ'SRrang = 1.959 ± 0.077. Agreement between the two values is reached for langβ r rang = 0.45 ± 0.25, consistent with mild radial anisotropy. This agreement supports the robustness of our results, despite the increase in mass-to-light ratio with total galaxy mass: M eff vprop L 1.363±0.056 V,eff. We conclude that massive ETGs are structurally close to homologous with close to isothermal total density profiles (lsim10% intrinsic scatter) and have at most some mild radial anisotropy. Our results provide new observational limits on galaxy formation and evolution scenarios, covering 4 Gyr look-back time.

Dates et versions

hal-03646258 , version 1 (19-04-2022)

Identifiants

Citer

L. V. E. Koopmans, A. Bolton, T. Treu, O. Czoske, M. W. Auger, et al.. The Structure and Dynamics of Massive Early-Type Galaxies: On Homology, Isothermality, and Isotropy Inside One Effective Radius. The Astrophysical journal letters, 2009, 703, pp.L51-L54. ⟨10.1088/0004-637X/703/1/L51⟩. ⟨hal-03646258⟩
6 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More