Pulsars in supernova remnants

Abstract

ABSTRACT A comparative analysis of the properties of 60 pulsars located in supernova remnants (SNRs) was carried out. We found that (1) anomalous X-ray pulsars (AXPs) and soft gamma repeaters (SGRs) are characterized by longer periods and higher values of period derivatives, (2) the remainder of the pulsars in this sample have shorter periods compared to the bulk of radio pulsars, (3) rotation of their neutron stars is braking faster, (4) this braking seems unlikely to be solely a result of the loss of angular momentum through magnetic dipole radiation. Using the measured and the estimated braking indices of individual pulsars, we calculated their birth periods. We found that (1) AXPs/SGRs are formed with periods of order of several seconds at the time of birth, (2) the remainder of the pulsars show the wide distribution of initial periods from 13 to 1300 ms with no predominance of millisecond values. Estimates of angles β between the rotation axis and the magnetic moment of the neutron stars are obtained. We found that the distribution of these angles is very close to the uniform distribution. This suggests that pulsars are born with arbitrary values of β. We found that the radio luminosities of pulsars observed inside their SNRs are, on average, one order of magnitude less than the average for neutron stars outside their SNRs. While we note that our data set of pulsars within SNRs of 60 is rather small our findings suggest that these pulsars do not show a decrease in their radio luminosity during their evolution.