Size-Dependent Fresh Surface Signatures in Asteroid Families: Observational Evidence from Dual-Band Albedo Analysis

The spectral evolution of asteroid surfaces reflects the competition between space weathering and impact resurfacing. While previous studies have focused primarily on age-dating, the role of family population size has remained largely unexplored. Here we tested whether population-dependent collisional activity affects observable surface properties by analyzing 154 asteroid families using NEOWISE thermal infrared photometry, employing a family-averaged statistical approach validated by independent AKARI observations (variance reduction factor ∼ 3.4) and comprehensive error propagation analysis (median V-Dominance Index (VDI) uncertainty ∼0.13). We introduced the VDI as a statistical measure quantifying the incidence of extreme resurfacing signatures within families, operationally defined as the fraction of members with visible-to-infrared albedo ratios 𝑝V/𝑝IR > 1.2 (99.8th percentile of the main-belt distribution). Among tested parameters, family population size (𝑁) emerged as the dominant correlate of VDI across both silicaceous (S-complex: 𝑟s = 0.58) and carbonaceous (C-complex: 𝑟s = 0.44) taxonomic types, with fullsample correlation 𝑟s = 0.476 (𝑝 = 4.31 × 10−10). This correlation survived Monte Carlo permutation tests, binomial null model validation, and age-matched contrast analyses, and heliocentric independence tests (partial correlation 𝑟partial = 0.488). Percentile sensitivity analysis (Δ𝑟s = 0.38 across 95th–99.8th percentiles) demonstrated that VDI isolates rare resurfacing events detectable only at extreme thresholds. In families older than 2 Gyr, large populations maintained statistically significant fresh tails (𝑝 < 10−4), whereas small populations were saturated. These results are consistent with model predictions where massive families experience elevated collisional resurfacing rates that counteract spaceweathering saturation, though alternative mechanisms cannot be excluded.