5 research outputs found
Instability of Massive Scalar Fields in Kerr-Newman Spacetime
We investigate the instability of charged massive scalar fields in
Kerr-Newman spacetime. Due to the super-radiant effect of the background
geometry, the bound state of the scalar field is unstable, and its amplitude
grows in time. By solving the Klein-Gordon equation of the scalar field as an
eigenvalue problem, we numerically obtain the growth rate of the amplitude of
the scalar field. Although the dependence of the scalar field mass and the
scalar field charge on this growth rate agrees with the result of the analytic
approximation, the maximum value of the growth rate is three times larger than
that of the analytic approximation. We also discuss the effect of the electric
charge on the instability of the scalar field.Comment: 15 pages, 10 figures. Accepted for publication in Prog.Theor.Phy
Simulation of Acoustic Black Hole in a Laval Nozzle
A numerical simulation of fluid flows in a Laval nozzle is performed to
observe formations of acoustic black holes and the classical counterpart to
Hawking radiation under a realistic setting of the laboratory experiment. We
determined the Hawking temperature of the acoustic black hole from obtained
numerical data. Some noteworthy points in analyzing the experimental data are
clarified through our numerical simulation.Comment: 26 pages, published versio