Jr-Yue Hsiang(Institute of Astronomy, National Tsing Hua University, Hsinchu 30013, Taiwan), Hsiang-Kuang Chang(Institute of Astronomy, National Tsing Hua University, Hsinchu 30013, Taiwan; Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan; Center for Informatics and Computation in Astronomy (CICA), National Tsing Hua University, Hsinchu 30013, Taiwan)
Looking for potential phenomenological connections between pulsar’s timing properties and emissions from pulsar wind nebulae and their pulsars, we studied non-thermal X-ray emissions from 35 pulsar wind nebulae that have a detected pulsar in X-rays. Our main results are in the following: (1) Non-thermal 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 (E_dot ), consistent with earlier studies. Moreover, comparable significant relations with magnetic field strength at the light cylinder (Blc) are also found. This suggests that not only E_dot but also Blc plays an important role in understanding these non-thermal emissions. (2) Thermal X-ray emissions are detected in 12 pulsars among the 35 samples. With derived temperature as one additional parameter, we found that the power indices of pulsar’s non-thermal X-ray power-law spectra can be well described by a linear function of log P, log P_dot, and 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.