  Electron-only reconnection is a process recently observed in the Earth's
magnetosheath, where magnetic reconnection occurs at electron kinetic scales
with only electrons involved. Electron-only reconnection is likely to have a
significant impact on the energy conversion and dissipation of turbulence
cascades at kinetic scales. This paper investigates electron-only reconnection
under different intensities of strong guide fields via two-dimensional fully
kinetic Particle-in-Cell (PIC) simulations, focusing on electron heating. The
simulations are initialized with a force-free current sheet equilibrium under
various intensities of strong guide fields. The quadrupolar structures of the
out-of-plane magnetic field and asymmetric structures of density are found to
become narrower in space as the guide field increases. Electron velocities are
considerably larger than ion velocities, and the motion of both species is
notably affected by the strength of guide fields. Similarly to previous
experiments studies, electron temperature anisotropy along separatrices is
observed, which is found to be mainly caused by the variations of parallel
temperature. Both regions of anisotropy and parallel temperature
increase/decrease along separatrices become thinner with increasing guide
fields. Besides, we find a transition from a quadrupolar to a six-polar to an
eight-polar structure in temperature anisotropy and parallel temperature as the
guide field intensifies. Non-Maxwellian electron velocity distribution
functions (EVDFs) at different locations in the three simulations are observed.
Our results show that parallel electron velocity varies notably with different
guide field intensities and strong parallel electron heat flux is observed.
