2005/05/05 by Adi Nusser, É. Pointecouteau, Etienne Pointecouteau
Physics and Astronomy · #Amplitude #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Classical mechanics #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Galaxy formation and evolution #Galaxy rotation curve #Gravitation #Gravitational potential #Modified Newtonian dynamics #Perturbation (astronomy) #Physics #Quantum mechanics #RADIUS #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2005.09831.x
published as Mon.Not.Roy.Astron.Soc. 366 (2006) 969-976 · 8 pages, 7 figures, MNRAS submitted
arxiv created 2005/05/05 · openalex publication_date 2006/01/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We use a one-dimensional hydrodynamical code to study the evolution of spherically symmetric perturbations in the framework of modified Newtonian dynamics (MOND). The code evolves spherical gaseous shells in an expanding Universe by employing a MOND-type relationship between the fluctuations in the density field and the gravitational force, g. We focus on the evolution of initial density perturbations of the form δi~r−si for 0 < s < 3. A shell is initially cold and remains so until it encounters the shock formed by the earlier collapse of shells nearer to the centre. During the early epochs g is sufficiently large and shells move according to Newtonian gravity. As the physical size of the perturbation increases with time, g gets smaller and the evolution eventually becomes MOND-dominated. However, the density in the inner collapsed regions is large enough that they re-enter the Newtonian regime. The evolved gas temperature and density profiles tend to a universal form that is independent of the slope, s, and of the initial amplitude. An analytic explanation of this intriguing result is offered. Over a wide range of scales, the temperature, density and entropy profiles in the simulations depend on radius roughly like r0.5, r−1.5 and r1.5, respectively. We compare our results with XMM-Newton and Chandra observations of clusters. The temperature profiles of 16 observed clusters are either flat or show a mild decrease at R≳ 200 kpc. MOND profiles show a significant increase that cannot be reconciled with the data. Our simulated MOND clusters are substantially denser than the observed clusters. It remains to be seen whether these difficulties persist in three-dimensional hydrodynamical simulations with generic initial conditions.