2014/04/07 by O. Brauer, H. A. Camargo, M. Socolovsky · 2 citations
Physics and Astronomy · #gr-qc #msc:83C57
paper · pdf · doi:10.1007/s10773-014-2225-3
13 pages, 6 figures
arxiv created 2014/04/07 · arxiv updated 2015/06/19
The purpose of the present article is to show that the Newman-Janis and Newman et al algorithm used to derive the Kerr and Kerr-Newman metrics respectively, automatically leads to the extension of the initial non negative polar radial coordinate r to a cartesian coordinate r' running from -∞ to +∞, thus introducing in a natural way the region -∞ < r' < 0 in the above spacetimes. Using Boyer-Lindquist and ellipsoidal coordinates, we discuss some geometrical aspects of the positive and negative regions of r', like horizons, ergosurfaces, and foliation structures.