  I present modeling of the X-ray pulsations from the central compact object
(CCO) PSR J1852+0040 in the Galactic supernova remnant Kesteven 79. In the
context of thermal surface radiation from a rotating neutron star, a
conventional polar cap model can reproduce the broad, large-amplitude X-ray
pulse only with a "pencil plus fan" beam emission pattern, which is
characteristic of strongly magnetized ($\gtrsim$10^12 Gauss) neutron star
atmospheres, substantially stronger than the ~10^10 Gauss external dipole field
inferred from the pulsar spin-down rate. This discrepancy can be explained by
an axially displaced dipole. For other beaming patterns, it is necessary to
invoke high-aspect-ratio emitting regions that are greatly longitudinally
elongated, possibly due to an extremely offset dipole. For all assumed emission
models, the existence of strong internal magnetic fields ($\gtrsim$10^14}
Gauss) that preferentially channel internal heat to only a portion of the
exterior is required to account for the implied high-temperature contrast
across the stellar surface. This lends further observational evidence in
support of the "hidden" strong magnetic field scenario, in which CCOs possess
strong submerged magnetic fields that are substantially stronger than the
external dipole field, presumably due to burial by fallback of supernova
ejecta. I also conduct phase-resolved X-ray spectroscopy and find no evidence
for prominent spin-phase-dependent absorption features that could be produced
by cyclotron absorption/scattering.
