Cluster Models

Combined N-body/hydrodynamic simulations produce in general very realistic cluster models. The simulations can in general reproduce cluster morphologies and other parameters known from observations quite well. The temperatures of the X-ray emitting intra-cluster gas are typically very well simulated. Also the spatial distributions are realistic. For the dark matter component the so-called NFW profile (Navarro et al. 1995) is usually found, while the gas profile is well fit by the so-called /3-profile (Cavaliere & Fusco-Femiano 1976).

The models can discriminate between cosmological parameters. Simulations on large scales show distinctly different distributions of matter for a mean matter density value of f2m = 1 and for Qm = 0.3 (Ostriker & Cen 1996; Thomas et al. 1998; Jenkins et al. 1998). While in the iim = 0.3 models the distribution changes only slightly between a red-shift z=l and now, in the ftm = 1 model significant differences are visible in the same time interval. Many smaller structures merge to form larger structures, so that the distribution looks much less smooth at z=0 than at z=l. A distinction between models and models is more difficult, because there are only small differences between these models.

By plotting cuts through the models at particular interesting planes like for example a plane containing the collision axis, or by plotting projections of the models onto different planes, one can follow every detail of the evolution. Interesting quantities are for instance cuts in the ICM density, the velocities (see Fig. 8.1) projections like the X-ray emission, the X-ray emission-weighted temperature and/or the particle positions are useful (see Fig. 8.2).

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