  Isolated neutron stars are seen in x-rays through their nonthermal and/or
surface thermal emissions. XMM-Newton observations of the Geminga pulsar show a
43 electron volt spectrum from the whole neutron star surface, as well as a
power-law component above 2 kiloelectron volts. In addition, we have detected a
hot (170 electron volts) thermal emission from an 60-meter-radius spot on the
pulsar s surface. Such a thermal emission, only visible at selected phase
intervals, may be coming from polar hot spot(s), long thought to exist as a
result of heating from magnetospheric accelerated particles. It may provide the
missing link between the x-ray and gamma-ray emission of the pulsar.
