Abstract
To look for possible phenomenological connections between pulsar's timing properties and emissions from pulsar wind nebulae and their pulsars, we studied the power-law component of the X-ray emissions from 35 pulsar wind nebulae which have a detected pulsar in X-rays. Our major results are in the following: (1) The power-law component of the X-ray luminosities, in the energy range from 0.5 keV to 8 keV, of the nebulae and of the pulsar both show a strong correlation with the pulsar spin-down power ( Ė ), consistent with earlier studies. However, equally significant correlations with the magnetic field strength at the light cylinder ( B_(\rm lc) ) are also found. The similar significance level of the correlations withĖand withB_(\rm lc)suggests that not onlyĖbut alsoB_(\rm lc)plays an important role in understanding these power-law emissions. (2) Thermal X-ray emissions are detected in 12 pulsars among the 35 samples. With derived temperature as one additional variable, we found that the photon indices of pulsar's non-thermal X-ray power-law spectra can be well described by a linear function of\log P ,\log{Ṗ}{}{a}nd temperature logarithm\log T . It indicates that the surface temperature of neutron stars plays an important role in determining the energy distribution of the radiating pair plasma in pulsar's magnetospheres.