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| Paper: |
Power-law Magnetic Field Decay and Constant Core Temperatures of Magnetars, Normal and
Millisecond Pulsars |
| Volume: |
451, 9th Pacific Rim Conference on Stellar Astrophysics |
| Page: |
253 |
| Authors: |
Xie, Y.; Zhang, S |
| Abstract: |
The observed correlations, between the characteristic ages and
dipole surface magnetic field strengths of all pulsars, can be well
explained by magnetic field decay with core temperatures of
2×108 K, ∼2×107 K, and ∼105 K, for
magnetars, normal radio pulsars, and millisecond pulsars,
respectively; assuming that their characteristic ages are about two
orders of magnitude larger than their true ages, the required core
temperatures may be reduced by about a factor of 10. The magnetic
decay follows a power-law and is dominated by the solenoidal
component of the ambipolar diffusion mode. In this model, all NSs
are assumed to have the same initial magnetic field strength, but
different core temperature which does not change as the magnetic field
decays. This suggests that the key distinguishing property between
magnetars and normal pulsars is that magnetars were born much hotter
than normal pulsars, and thus have much longer magnetic field decay
time scales, resulting in higher surface magnetic field strength
even with the same ages of normal pulsars. The above conclusion
agrees well with the observed correlations between the surface
temperatures of magnetars and other young NSs, which do not agree
with the cooling dominated evolution of neutron stars. This suggests
a possible scenario that heating, perhaps due to magnetic field
decay, balances neutron star cooling for observed pulsars. |
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