Estimating Properties of a Young Pulsar through X-ray Observations - An Investigation of Parameter Dependence

Abstract: Studying the properties of newborn neutron stars is a complicated matter since they cannot be directly observed. Neutron stars are born when some massive stars go supernova (SN), where the expelled material from the explosion goes on to shield the young neutron star from our view by absorbing its radiation. To estimate properties such as their flux, luminosity and magnetic field strength, upper limits can be found by modeling the emission and absorption and then performing spectral fitting. The assumptions made when modeling can cause the results to differ, this thesis investigates which parameters in the model have the most impact by analysing an X-ray observation of SN 1909A. The varied model parameters are the photon index of the neutron star emission, the density of the SN ejecta, and the composition of the ejecta material. The density can vary depending on the line of sight since SN explosions are asymmetrical, and it is found that this parameter carries most significance, with maximal result variations of about 55% for most ejecta compositions. The least significant parameter is the assumed photon index of the emission from the neutron star, this is found to only cause maximal variations of around 24%. Furthermore, the upper limits on the total luminosity computed by assuming different model parameters, differ by a factor 2.5 at most. The minimum upper limit to the total luminosity of the neutron star of SN 1909A is found to be L_min = 3.6 ' 10^6 L⊙ and the corresponding relation between its rotational period and magnetic field is B < 1.88 ' 10^20 P^2 G s^-1.