Do we really see homogeneity? 361Figure 12.8. The spatial distribution of x-ray clusters in the REFLEX survey, out to
600 h−^1 Mpc. Note how, despite the coarser mapping of large-scale structure, filamentary
superclusters (‘chains’ of clusters) are clearly visible.
biasing scenario where clusters represent the high, rare peaks of the mass density
distribution. This result strongly corroborates the simpler, reassuring view that at
least above∼ 5 h−^1 Mpc the galaxy and mass distributions are linked by a simple
constant bias.
12.5.2 ‘Peaks and valleys’ in the power spectrum
Most of the discussion so far has concentrated on the beauty of finding ‘smooth’
simple shapes forξ(r)orP(k), as symptoms of an underlying order of Nature.
Rather than being a demonstration of Nature’s inclination for elegance, however,
this smoothness and simplicity might simply indicate our ignorance and lack of
data. In fact, while smooth power spectra are predicted in models dominated by