Statistical tests of young radio pulsars with/without supernova remnants: implying two origins of neutron stars

Abstract

ABSTRACT The properties of the young pulsars and their relations to the supernova remnants (SNRs) have been the interesting topics. At present, 383 SNRs in the Milky Way Galaxy have been published, which are associated with 64 radio pulsars and 46 pulsars with high-energy emissions. However, we noticed that 630 young radio pulsars with the spin periods of less than half a second have been not yet observed the SNRs surrounding or nearby them, which arises a question of that could the two types of young radio pulsars with/without SNRs hold the distinctive characteristics? Here, we employ the statistical tests on the two groups of young radio pulsars with (52) and without (630) SNRs to reveal if they share the different origins. Kolmogorov–Smirnov (K–S) and Mann–Whitney–Wilcoxon (M–W–W) tests indicate that the two samples have the different distributions with parameters of spin period (P), derivative of spin period ($\dot{P}$), surface magnetic field strength (B), and energy loss rate ($\dot{E}$). Meanwhile, the cumulative number ratio between the pulsars with and without SNRs at the different spin-down ages decreases significantly after $\rm 10\!-\!20\, kyr$. So we propose that the existence of the two types of supernovae (SNe), corresponding to their SNR lifetimes, which can be roughly ascribed to the low- and high-energy SNe. Furthermore, the low-energy SNe may be formed from the $\rm 8\!-\!12\, M_{\odot }$ progenitor, e.g. possibly experiencing the electron capture, while the main-sequence stars of $\rm 12\!-\!25\, M_{\odot }$ may produce the high-energy SNe probably by the iron core collapse.