2025ApJ...981..100X

To date, over 4000 pulsars have been detected. In this study, we identify 231 X-ray counterparts of Australia Telescope National Facility (ATNF) pulsars by performing a spatial cross match across the Chandra, XMM-Newton observational catalogs. This data set represents the largest sample of X-ray counterparts ever compiled, including 98 normal pulsars (NPs) and 133 millisecond pulsars (MSPs). Based on this significantly expanded sample, we re-establish the correlation between X-ray luminosity and spin-down power, given by ${L}_{{\rm{X}}}\propto {\dot{E}}^{0.85\pm 0.05}$ across the whole X-ray band. The strong correlation is also observed in hard X-ray band, while in soft X-ray band there is no significant correlation. Furthermore, L_X shows a strong correlation with spin period and characteristic age for NPs. For the first time, we observe a strongly positive correlation between L_X and the light cylinder magnetic field (B_lc) for MSPs, with both NPs and MSPs following the relationship ${L}_{{\rm{X}}}\propto {B}_{{\rm{lc}}}^{1.14}$, consistent with the outer-gap model of pulsars that explains the mechanism of X-ray emission. Additionally, we investigate potential X-ray counterparts for Galactic Plane Pulsar Snapshot pulsars, finding a lower likelihood of detection compared to ATNF pulsars.