A topological method for geodesic connectedness of space–times: Outer Kerr space–time

2002 ◽  
Vol 43 (10) ◽  
pp. 4861 ◽  
Author(s):  
José Luis Flores ◽  
Miguel Sánchez
2015 ◽  
Vol 30 (11) ◽  
pp. 1550052 ◽  
Author(s):  
Masakatsu Kenmoku ◽  
Y. M. Cho

The superradiance phenomena of massive bosons and fermions in the Kerr space–time are studied in the Bargmann–Wigner formulation. In case of bi-spinor, the four independent components spinors correspond to the four bosonic freedom: one scalar and three vectors uniquely. The consistent description of the Bargmann–Wigner equations between fermions and bosons shows that the superradiance of the type with positive energy (0 < ω) and negative momentum near horizon (p H < 0) is shown not to occur. On the other hand, the superradiance of the type with negative energy (ω < 0) and positive momentum near horizon (0 < p H ) is still possible for both scalar bosons and spinor fermions.


2020 ◽  
Vol 35 (05) ◽  
pp. 2050024
Author(s):  
Reinoud Jan slagter ◽  
Christopher Levi Duston

We investigate the space–time of a spinning cosmic string in conformal invariant gravity, where the interior consists of a gauged scalar field. We find exact solutions of the exterior of a stationary spinning cosmic string, where we write the metric as [Formula: see text], with [Formula: see text] a dilaton field which contains all the scale dependences. The “unphysical” metric [Formula: see text] is related to the [Formula: see text]-dimensional Kerr space–time. The equation for the angular momentum [Formula: see text] decouples, for the vacuum situation as well as for global strings, from the other field equations and delivers a kind of spin-mass relation. For the most realistic solution, [Formula: see text] falls off as [Formula: see text] and [Formula: see text] close to the core. The space–time is Ricci flat. The formation of closed timelike curves can be pushed to space infinity for suitable values of the parameters and the violation of the weak energy condition can be avoided. For the interior, a numerical solution is found. This solution can easily be matched at the boundary on the exterior exact solution by special choice of the parameters of the string. This example shows the power of conformal invariance to bridge the gap between general relativity and quantum field theory.


2009 ◽  
Vol 18 (12) ◽  
pp. 5575-5582
Author(s):  
Ren Jun ◽  
Jia Meng-Wen ◽  
Yuan Chang-Qing

2012 ◽  
Vol 45 (1) ◽  
pp. 203-227 ◽  
Author(s):  
Horst Reinhard Beyer ◽  
Miguel Alcubierre ◽  
Miguel Megevand ◽  
Juan Carlos Degollado

1987 ◽  
Vol 28 (4) ◽  
pp. 859-887 ◽  
Author(s):  
Brian Punsly
Keyword(s):  

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