Scale-Dependent Multifractal Structure in the Planck 2018 CMB: Evidence from Needlet-Based Detrended Fluctuation Analysis

We present the first application of multifractal detrended fluctuation analysis (MFDFA) to the Planck 2018 SMICA temperature map at full resolution (Nside = 2048). Using a needlet-based scale decomposition, we compute generalized Hurst exponents h(q) across seven angular scale bands (l = 2-2500). Comparing against 500 Gaussian simulations with identical power spectra, we find no significant excess multifractality at large angular scales (l < 1500), confirming that large-scale CMB multifractality is driven by long-range correlations rather than non-Gaussian processes. At the smallest scales (l = 1500-2500), we detect 9.6-sigma excess multifractality tentatively attributed to non-Gaussian instrumental noise. These results extend Movahed et al.'s (2011) WMAP conclusion to Planck resolution. Includes analysis code (Python) and 6 publication-quality figures.