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

Abstract

The spectral evolution of asteroid surfaces reflects the competition between space weathering and impact resurfacing. While previous studies focused primarily on age-dating, the role of family population size remains largely unexplored. We tested whether population-dependent collisional activity affects observable surface properties by analyzing 154 asteroid families using NEOWISE thermal infrared photometry, validated by independent AKARI observations and error propagation analysis. We introduced the V-Dominance Index (VDI) to quantify the incidence of extreme resurfacing signatures within families, defined as the fraction of members with visible-to-infrared albedo ratios p_V/p_IR > 1.2. Among tested parameters, family population size (N) emerged as the dominant correlate of VDI across both silicaceous (S-complex: r_s = 0.58) and carbonaceous (C-complex: r_s = 0.44) taxonomic types, with a full-sample correlation r_s = 0.476 (p = 4.31 x 10^-10). This correlation survived Monte Carlo permutation tests, binomial null model validation, age-matched contrast analyses, and heliocentric independence tests. Percentile sensitivity analysis 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 indicate that massive families experience elevated collisional resurfacing rates that counteract space weathering saturation.