O. Tanimura et S. Hori, SOLUTION WITH REAL VALUE OF DEFORMATION PARAMETER FOR ERNST EQUATION IN GRAVITATIONAL-FIELD CAUSED BY ROTATING SOURCE, Progress of theoretical physics, 99(5), 1998, pp. 783-799
Starting with the Weyl solution that is known to be valid for ally rea
l value of the deformation parameter delta, the solution of the Ernst
equation ill an axially symmetric gravitational field caused by a rota
ting source is given in a perturbative expansion of the variables lamb
da(= q(2)/p(2)) and b(= y(2)-1) for a real value of delta. The proof o
f the validity of the solution is given to first order in lambda and a
ll orders in b.