Non-vacuum Metrics for the Newman-Unti-Tamburino Background: A Coordinate-Free Approach to Diverging and Twisting Solutions
摘要
The geometry of the Newman-Unti-Tamburino (NUT) vacuum solution is characterized as the unique Petrov Type D vacuum metric such that the two double principal null directions form an integrable distribution. We study expanding and twisting non-vacuum Type D metrics in this geometry, with the additional assumption