Back to the Starting Point: On the Simulation of the Initial Magnetic Fields and Spin Periods of Nonaccreting Pulsars

Neutron stars (NSs) play essential roles in modern astrophysics. The magnetic fields and spin periods of newborn (zero-age) NSs have a large impact on the further evolution of NSs, which are, however, poorly explored in observations due to the difficulty of finding newborn NSs. In this work, we aim to infer the magnetic fields and spin periods (B (i) and P (i)) of zero-age NSs from the observed properties of the NS population. We select nonaccreting NSs whose evolution is solely determined by magnetic dipole radiation. We find that both B (i) and P (i) can be described by lognormal distribution, and the fitting sensitively depends on our parameters.