CMB Power Spectrum (Toy)

What you are seeing: the angular power spectrum $D_\ell = \ell(\ell+1)C_\ell/2\pi$ of CMB temperature fluctuations. The first acoustic peak at $\ell \sim 220$ measures the geometry; peak ratios constrain $\Omega_b$ ; the damping tail measures Silk damping. Toy model only.

Figure 1. Toy CMB power spectrum with adjustable parameters.

l_peak1220

l_damp2000

WHAT TO TRY

Slide l_peak1 (first acoustic peak): it encodes the geometry of the universe. Moving it is what a change in spatial curvature would do to the observed spectrum.
Pull l_damp inward: the high-l damping tail rolls off sooner, mimicking stronger Silk damping as photons diffuse out of small-scale perturbations before recombination.
Read the peak structure: the first peak sets the sound-horizon angle, and the peak height ratios are what constrain the baryon density in the real fit.