Wavelet-Scattering Signatures of Fuzzy Dark Matter in Simulated 21 cm Brightness-Temperature Maps

We study the effect of fuzzy dark matter (FDM) on the multiscale morphology of simulated redshifted 21,cm maps during Cosmic Dawn and the Epoch of Reionization. Using FDM-modified 21cmFAST light cones, we apply the two-dimensional wavelet scattering transform (WST) to matched 2,MHz map products. The first-order coefficients S 1(j) summarize wavelet-band amplitudes, while the normalized second-order ratio R=S 2/S 1(j 1) measures ordered cross-scale modulation. FDM shifts and reshapes both summaries through delayed halo and source formation. We compare a two-dimensional power spectrum (PS), WST, and their combination on the same transferred and noisy maps. In this controlled local Fisher analysis, PS+WST reduces the marginalized errors on the FDM mass, effective X-ray emissivity normalization, and ionizing efficiency by approximately a factor of 1.8 relative to the matched two-dimensional PS baseline, although the dominant mass-heating degeneracy remains. An idealized three-wedge test shows that R is less reshaped at the coefficient level than S 1. The covariance includes thermal noise conditional on one fiducial light cone but not cosmic variance or foreground residuals; the results are therefore relative information comparisons, not survey forecasts or a demonstration of superiority over a full three-dimensional PS analysis.