Stacked y maps and corresponding y profiles using different sizes of masks for galaxy clusters: 2 × R₅₀₀ (left panel), 3 × R₅₀₀ (middle panel) and 4 × R₅₀₀ (right panel). The mean y values in the superclusters are estimated to be y = (3.4 ± 1.3) × 10⁻⁸ (2 × R₅₀₀), y = (3.5 ± 1.4) × 10⁻⁸ (3 × R₅₀₀), and y = (3.1 ± 2.0) × 10⁻⁸ (4 × R₅₀₀), respectively. In our analysis, we adopt a size of 3 × R₅₀₀ for the mask.