  Within the context of quantum field theory in curved spacetimes, Hacyan and
Sarmiento defined the vacuum stress-energy tensor with respect to the
accelerated observer. They calculated it for uniform acceleration and circular
motion, and derived that the rotating observer perceives a flux. Mane related
the flux to synchrotron radiation. In order to investigate the relation between
the vacuum stress and bremsstrahlung, we estimate the stress-energy tensor of
the electromagnetic field generated by a point charge, at the position of the
charge. We use the retarded field as a self-field of the point charge.
Therefore the tensor diverges if we evaluate it as it is. Hence we remove the
divergent contributions by using the expansion of the tensor in powers of the
distance from the point charge. Finally, we take an average for the angular
dependence of the expansion. We calculate it for the case of uniform
acceleration and circular motion, and it is found that the order of the vacuum
stress multiplied by $\pi\alpha$ ($\alpha=e^2/\hbar c$ is the fine structure
constant) is equal to that of the self-stress. In the Appendix, we give another
trial approach with a similar result.
