Paper detail

Growth of the Magnetic Field in Young Neutron Stars

Rotation Powered-Pulsars are subjected to long-term changes in their period of rotation, which are measured by timing observations of their rotation frequency and its derivatives ($Ω$, $\dotΩ$, $\ddotΩ$). If the spin-down is solely due to dipolar radiation, the braking index should be $n=3$. To date, only a handful of braking indices have been estimated for young pulsars, and in all cases one observes that $n<3$. These observations suggest that there are complex spin-down processes taking place in the pulsar that are not fully well understood. In the present work we revisit the spin-down of young pulsars by considering a possible magnetic field growth due ohmic diffusion. In order to perform such study we perform calculations with phenomenological growth functions for the magnetic field. With that we are able to calculate the spin evolution of the neutron star with all relevant quantities. We show that such approach could explain the low values of $n$ in very young neutron stars and may be relevant to explain why a small group of neutron stars (including central compact objects) exhibit no evidence of a standard magnetic field. We find that the possibility of magnetic field growth are relevant to the spin evolution of young neutron stars, and therefore should not be neglected.