The abundance and clustering of dark haloes in the standard ΛCDM cosmogony
Much evidence suggests that we live in a flat cold dark matter universe with a cosmological constant. Accurate analytic formulae are now available for many properties of the dark halo population in such a Universe. Assuming current ‘concordance’ values for the cosmological parameters, we plot halo abundance against redshift as a function of halo mass, halo temperature, the fraction of cosmic matter in haloes, halo clustering strength, and the clustering strength of the z= 0 descendants of high-redshift haloes. These plots are useful for understanding how nonlinear structure grows in the model. They demonstrate a number of properties that may seem surprising, for example: 109 M⊙ haloes are as abundant at z= 20 as L* galaxies are today; 106 K haloes are equally abundant at z= 8 and at z= 0; 10 per cent of all matter is currently in haloes hotter than 1 keV, while more than half is in haloes too cool to trap photo-ionized gas; 1 per cent of all matter at z= 15 is in haloes hot enough to ionize hydrogen; haloes of given mass or temperature are more clustered at higher redshift; haloes with the abundance of present-day L* galaxies are equally clustered at all z < 20; the metals produced by star-formation at z > 10 are more clustered at z= 0 than are L* galaxies.