Fig. 5: Comparing the measured power spectrum with that of the CMB.
From: Analogue cosmological particle creation in an ultracold quantum fluid of light

a The static structure factor for τ > 0. The wavenumbers are normalized such that unity can be compared with the first peak of the CMB spectrum in (b). b The power spectrum of temperature fluctuations in the CMB, as a function of multipole number, from Ref. 36.