Concentration, spin and shape of dark matter haloes as a function of the cosmological model: WMAP1, WMAP3 and WMAP5 results

We investigate the effects of changes in the cosmological parameters between the Wilkinson Microwave Anisotropy Probe (WMAP) 1st, 3rd and 5th year results on the structure of dark matter haloes. We use a set of simulations that cover five decades in halo mass ranging from the scales of dwarf galaxies (V(c) approximate to 30 km s(-1)) to clusters of galaxies (V(c) approximate to 1000 km s(-1)). We find that the concentration mass relation is a power law in all three cosmologies. However, the slope is shallower and the zero-point is lower moving from WMAP1 to WMAP5 to WMAP3. For haloes of mass logM(200)/[h(-1) M(circle dot)] = 10, 12 and 14 the differences in the concentration parameter between WMAP1 and WMAP3 are a factor of 1.55, 1.41 and 1.29, respectively. As we show, this brings the central densities of dark matter haloes in good agreement with the central densities of dwarf and low surface brightness galaxies inferred from their rotation curves, for both the WMAP3 and WMAP5 cosmologies. We also show that none of the existing toy models for the concentration-mass relation can reproduce our simulation results over the entire range of masses probed. In particular, the model of Bullock et al. fails at the higher mass end (M greater than or similar to 10(13) h(-1) M(circle dot)), while the NFW model of Navarro, Frenk and White fails dramatically at the low-mass end (M less than or similar to 10(12) h(-1)M(circle dot)). We present a new model, based on a simple modification of that of Bullock et al., which reproduces the concentration-mass relations in our simulations over the entire range of masses probed (10(10) less than or similar to M less than or similar to 10(15) h(-1)M(circle dot)). Haloes in the WMAP3 cosmology (at a fixed mass) are more flatted compared to the WMAP1 cosmology, with a medium to long axis ration reduced by approximate to 10 per cent. Finally, we show that the distribution of halo spin parameters is the same for all three cosmologies.