  Central compact objects are young neutron stars emitting thermal X-rays with
bolometric luminosities $L_X$ in the range $10^{32}$-$10^{34}$ erg/s.
Gourgouliatos, Hollerbach and Igoshev recently suggested that peculiar emission
properties of central compact objects can be explained by tangled magnetic
field configurations formed in a stochastic dynamo during the proto-neutron
star stage. In this case the magnetic field consists of multiple small-scale
components with negligible contribution of global dipolar field. We study
numerically three-dimensional magneto-thermal evolution of tangled crustal
magnetic fields in neutron stars. We find that all configurations produce
complicated surface thermal patterns which consist of multiple small hot
regions located at significant separations from each other. The configurations
with initial magnetic energy of $2.5-10\times 10^{47}$ erg have temperatures of
hot regions that reach $\approx 0.2$ keV, to be compared with the bulk
temperature of $\approx 0.1$ keV in our simulations with no cooling. A factor
of two in temperature is also seen in observations of central compact objects.
The hot spots produce periodic modulations in light curve with typical
amplitudes of $\leq 9-11$ %. Therefore, the tangled magnetic field
configuration can explain thermal emission properties of some central compact
objects.
