  The cooling theory of neutron stars is corroborated by its comparison with
observations of thermally emitting isolated neutron stars and accreting neutron
stars in binary systems. An important ingredient for such an analysis is the
age of the object, which, typically, is obtained from the spin-down history.
This age is highly uncertain if the object's magnetic field varies appreciably
over time. Other age estimators, such as supernova remnant ages and kinematic
ages, only apply to few handful of neutron stars. We conduct a population
synthesis study of the nearby isolated thermal emitters and obtain their ages
statistically from the observed luminosity function of these objects. We argue
that a more sensitive blind scan of the galactic disk with the upcoming space
telescopes can help to constrain the ages to higher accuracy.
