Typical values of the surface magnetic fields of radio pulsars are . In Figure 41 we compare plots of and for the pure iron envelope with of a neutron star with and km with and without a magnetic field. The approximation for the crust is used. Typical values of the surface magnetic field of radio pulsars are . At such magnetic fields, the effect of is seen only in the outer envelope, which is cm thick. We can see there quantum oscillations of the density as a function of depth. They are associated with the filling of the lowest Landau levels by the electrons (Section 2.2). Increasing to G, associated with the most magnetized radio pulsars, leads to much deeper magnetization of the crust, down to the depth of 30 m, where the prevailing density reaches . The effect of the magnetic field in the outer 30 cm of the crust is dramatic; in spite of a gravitational acceleration , the density is only slowly decreasing, and is still at 10 cm depth, ten times higher than in a nonmagnetized envelope at the same depth. So, magnetized iron plasma is “condensed”, and much less compressible than nonmagnetized (Section 2.2). At 1013 G, the Landau level begins to be populated only at 4 105 g cm–3 (depth 3 m), to be compared with 2 104 g cm–3 (depth 30 cm) at 1012 G. It should be stressed that, as the surface temperature at pulsar age 103 – 104 y is , inclusion of will weaken the magnetization effects on the structure of the crust .
Typical surface magnetic fields of magnetars are 1015 G. In Figure 42 we see that for , the effect of such a huge on the crust EoS is strong and becomes dramatic at lower . For example, at 107 g cm–3, the matter pressure decreases by two orders of magnitude, compared to the case. The Landau level begins to be populated only at 108.7 g cm–3, at a depth of about 50 m.
This work is licensed under a Creative Commons License.