19 research outputs found
Rotation in vacuum and scalar background: are there alternatives to Newman-Janis algorithm?
The Newman-Janis algorithm is the standard approach to rotation in general
relativity which, in vacuum, builds the Kerr metric from the Schwarzschild
spacetime. Recently, we have shown that the same algorithm applied to the
Papapetrou antiscalar spacetime produces a rotational metric devoid of horizons
and ergospheres. Though exact in the scalar sector, this metric, however,
satisfies the Einstein equations only asymptotically. We argue that this
discrepancy between geometric and matter parts (essential only inside
gravitational radius scale) is caused by the violation of the Hawking-Ellis
energy conditions for the scalar energy-momentum tensor. The axial potential
functions entering the metrics appear to be of the same form both in vacuum and
scalar background, and they also coincide with the linearized Yang-Mills field,
which might hint at their common non-gravitational origin. As an alternative to
the Kerr-type spacetimes produced by Newman-Janis algorithm we suggest the
exact solution obtained by local rotational coordinate transformation from the
Schwarzschild spacetime. Then, comparison with the Kerr-type metrics shows that
the Lense-Thirring phenomenon might be treated as a coordinate effect, similar
to the Coriolis force.Comment: Accepted in IJMP