We test with gravitational lensing (GL) data the dark matter (DM) halos embedding the luminous baryonic component of galaxy clusters; our benchmark is provided by their two-stage cosmogonical development that we compute with its variance, and by the related "α-profiles" we derive. The latter solve the Jeans equation for the self-gravitating, anisotropic DM equilibria, and yield the radial runs of the density ρ(r) and the velocity dispersion σ2 r (r) in terms of the DM "entropy" K ≡ σ2 r /ρ2/3 vprop r α highlighted by recent N-body simulations; the former constrains the slope to the narrow range α ≈ 1.25-1.3. These physically based α-profiles meet the overall requirements from GL observations, being intrinsically flatter at the center and steeper in the outskirts relative to the empirical Navarro, Frenk, & White formula. Specifically, we project them along the line of sight and compare with a recent extensive data set from strong and weak lensing observations in and around the cluster A1689. We find an optimal fit at both small and large scales in terms of a halo constituted by an early body with α ≈ 1.25 and by recent extensive outskirts, that make up an overall mass 1015 M sun with a concentration parameter c ≈ 10 consistent with the variance we compute in the ΛCDM cosmogony. The resulting structure corresponds to a potential well shallow in the outskirts as that inferred from the X rays radiated from the hot electrons and baryons constituting the intracluster plasma.
|Titolo:||Structure and History of Dark Matter Halos Probed with Gravitational Lensing|
|Autori:||Lapi, A.; Cavaliere, A.|
|Data di pubblicazione:||2009|
|Digital Object Identifier (DOI):||10.1088/0004-637X/695/2/L125|
|Appare nelle tipologie:||1.1 Journal article|