Evolution of the magnetic field in neutron stars

We propose a general method to self-consistently study the quasistationary evolution of the magnetic field in the cores of neutron stars. The traditional approach to this problem is critically revised. Our results are illustrated by calculation of the typical timescales for the magnetic field dissipation as functions of temperature and the magnetic field strength.

Figure 1

The magnetic field decay timescale ${\tau }_{\mathrm{B}}=2E_{\mathrm{B}}/{\dot{E}}_{\mathrm{B}}$ in the case of the nonequilibrium MUrca processes as the main mechanism restoring chemical equilibrium. From left to right: $B_{\mathrm{T}\max }/B_{\text{Pmax}}=0$, 1, 2.29. Thin white lines correspond to $\log {\tau }_{\mathrm{B}}=\text{const}$. Thick black lines in the ($\log \tilde{B}-\log T$) plane separate the regions where one of the three dissipation mechanisms (ambipolar diffusion, MUrca processes, or Ohmic decay) is most efficient.

Figure 2

The same as in Fig. 1 but for the nonequilibrium DUrca process as the main mechanism that restores chemical equilibrium.