A simulated τCDM cosmology cluster catalogue: the NFW profile and the temperature–mass scaling relations

We have extracted over 400 clusters, covering more than two decades in mass, from three simulations of the τ CDM cosmology. This represents the largest uniform catalogue of simulated clusters ever produced. The clusters exhibit a wide variety of density profiles. Only a minority are well-fitted in their outer regions by the widely used density profile of Navarro, Frenk & White (NFW), which is applicable to relaxed haloes. Others have steeper outer density profiles, show sharp breaks in their density profiles, or have significant substructure. If we force a fit to the NFW profile, then the best-fitting concentrations decline with increasing mass, but this is driven primarily by an increase in substructure as one moves to higher masses. The temperature–mass relations for properties measured within a sphere enclosing a fixed overdensity all follow the self-similar form, T ∝ M ^2/3; however, the normalization is lower than the value inferred for observed clusters. The temperature–mass relations for properties measured within a fixed physical radius are significantly steeper then this. Both can be accurately predicted using the NFW model.