2006/02/28 by Luca Zappacosta, L. Zappacosta, David A. Buote +9 · 5 citations
Physics and Astronomy · #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/505739
published as Astrophys.J.650:777-790,2006 · 15 pages, 11 figures, accepted for publication in ApJ. Minor changes to match published version
arxiv created 2006/05/12 · openalex publication_date 2006/10/18 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We present an X-ray analysis of the radial mass profile of the radio-quiet galaxy cluster A2589 between 0.015 and 0.25 r vir , using an XMM-Newton observation. Except for a ≈16 kpc shift of the X-ray center of the R = 45-60 kpc annulus, A2589 possesses a remarkably symmetrical X-ray image and is therefore an exceptional candidate for precision studies of its mass profile by applying hydrostatic equilibrium. The total gravitating matter profile is well described by the NFW model with c vir = 6.1 ± 0.3 and M vir = 3.3 ± 0.3 × 10 14 M ☉ ( r vir = 1.74 ± 0.05 Mpc), in excellent agreement with ΛCDM. When the mass of the hot intracluster medium is subtracted from the gravitating matter profile, the NFW model fitted to the resulting dark matter (DM) profile produces essentially the same result. However, when accounting for the stellar mass ( M * ) of the cD galaxy, the NFW fit to the DM profile substantially degrades in the central r ~ 50 kpc for reasonable values of M * / L V . Modifying the NFW DM halo by adiabatic contraction arising from the early condensation of stellar baryons in the cD galaxy further degrades the fit. The fit is improved substantially with a Sérsic-like model recently suggested by high-resolution N -body simulations but with an inverse Sérsic index, α ~ 0.5, that is a factor of ~3 higher than predicted. We argue that neither random turbulent motions nor magnetic fields can provide sufficient nonthermal pressure support to reconcile the XMM-Newton mass profile with adiabatic contraction of a CDM halo, assuming reasonable values of M * / L V . Our results support the scenario in which, at least for galaxy clusters, processes during halo formation counteract adiabatic contraction so that the total gravitating mass in the core approximately follows the NFW profile.