Maximum and standard deviation of temperature fluctuations for CMB photons that passed through a (100 Mpc)³ cosmological box. The box is populated with 10⁹ M_⊙ mergers according to a given volumetric merger rate, which are otherwise sampled uniformly in space, time, inclination, and orientation. The results are averaged over a total of ∼3 × 10⁴ realisations (pale lines), an both the mean (solid lines) and the standard deviation (shaded areas enclosed by black lines) of the realisations are shown.