In a previous work of ours, the most general family of Kerr deformations—admitting a Carter constant—has been presented. This time a simple, necessary and sufficient condition in order for the aforementioned family to have a separable Klein-Gordon equation is exhibited. In addition, we provide a solid theoretical foundation that the maximum number of free to be chosen radial functions is three.

中文翻译：

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关于Kerr黑洞变形，该变形允许Carter常数和波动方程可分离性的不变准则。

在我们先前的工作中，提出了最普通的Kerr变形族（允许Carter常数）。这次展示了简单，必要和充分的条件，以使上述族具有可分离的Klein-Gordon方程。此外，我们提供了坚实的理论基础，即自由选择的径向函数的最大数量为3。