Scatter plots of C_x with MC propagation and expansion speeds for all the events listed in Table A.1. The top panel is the scatterplot between C_x (estimated using γ = 5/3; as in Eq. (9)) and the MC propagation speed (⟨v⟩_MC). The correlation coefficient between C_x and ⟨v⟩_MC are r = 0.43, with p = 3.5 × 10⁻⁸ (for BG1) and r = 0.51, with p = 1.8 × 10⁻¹¹ (for BG2). The equation of the fitted lines corresponding to BG1 and BG2 are y = 0.25x − 75.65 and y = 0.24x − 73.28, respectively. The middle panel is the scatter plot between C_x (computed using γ = 5/3) and the MC expansion speed (v_exp), only for events with v_exp >  0. The correlation coefficients are r = 0.50, with p = 5.73 × 10⁻⁹ for BG1 and r = 0.63, with p = 1.9 × 10⁻¹⁴ for BG2. The equation of fitted lines are y = 0.72x + 4.82 and y = 0.73x + 2.73 corresponding to BG1 and BG2, respectively. The bottom panel is the scatter plot between C_x (calculated using γ = 5/3) and v_exp/⟨v⟩_MC (only for events with v_exp >  0). The correlation coefficients are r = 0.40, with p = 7.8 × 10⁻⁶(for BG1) and r = 0.50, with p = 1.2 × 10⁻⁸(for BG2). The equation of the fitted lines are y = 342.6x + 3.36 (for BG1) and y = 341.71x + 1.46 (for BG2). The small p-values imply a high statistical confidence in computing the r values in all three cases.