Left panel: the distribution of the phase lag between the X-ray main peak and the radio main peak of the Crab pulsar with bin size 5.8 × 10 ⁻⁴ periods. The dashed line represents the fitted Gaussian function with μ = −0.0101 and σ = 1.3 × 10 ⁻³. Right panel: the distribution of the separation between the two X-ray peaks with bin size 9.6 × 10 ⁻⁵ periods. The dashed line represents the fitted Gaussian function with μ = 0.4005 and σ = 2.5 × 10 ⁻⁴.