As CMB anisotropy is detected on smaller angular scales and large-scale structure surveys extend to larger regions, there is an increasing overlap in the spatial scale of inhomogeneities probed by these complementary techniques. This allows us to test the gravitational instability paradigm in general and then move on to finding cosmological models which can simultaneously explain the CMB and large-scale structure observations. Figure 5 shows this comparison for our compilation of CMB anisotropy observations (colored boxes) and of large-scale structure surveys (APM - Gaztañaga & Baugh 1998, LCRS - Lin et al. 1996, Cfa2+SSRS2 - Da Costa et al. 1994, PSCZ - Tadros et al. 1999, APM clusters - Tadros et al. 1998) including measurements of the dark matter fluctuations from peculiar velocities (Kolatt & Dekel, 1997) and the abundance of galaxy clusters (Viana & Liddle, 1996; Bahcall et al., 1997). Plotting CMB anisotropy data as measurements of the matter power spectrum is a model-dependent procedure, and the galaxy surveys must be corrected for redshift distortions, non-linear evolution, and galaxy bias (see Gawiser & Silk 1998 for detailed methodology.) Figure 5 is good evidence that the matter and radiation inhomogeneities had a common origin - the standard CDM model with a Harrison-Zel'dovich primordial power spectrum predicts both rather well. On the detail level, however, the model is a poor fit (2 / d.o.f.=2.1), and no cosmological model which is consistent with the recent Type Ia supernovae results fits the data much better. Future observations will tell us if this is evidence of systematic problems in large-scale structure data or a fatal flaw of the CDM model.
Figure 5. Compilation of CMB anisotropy detections (boxes) and large-scale structure observations (points with error bars) compared to theoretical predictions of standard CDM model. Height of boxes (and error bars) represents 1 uncertainties and width of boxes shows the full width at half maximum of each instrument's window function.lchdm00.ps