2,776 research outputs found
The double-Kerr equilibrium configurations involving one extreme object
We demonstrate the existence of equilibrium states in the limiting cases of
the double-Kerr solution when one of the constituents is an extreme object. In
the `extreme-subextreme' case the negative mass of one of the constituents is
required for the balance, whereas in the `extreme-superextreme' equilibrium
configurations both Kerr particles may have positive masses. We also show that
the well-known relation |J|=M^2 between the mass and angular momentum in the
extreme single Kerr solution ceases to be a characteristic property of the
extreme Kerr particle in a binary system.Comment: 12 pages, 3 figures, submitted to Class. Quantum Gra
On the physical interpretation of the delta=2 Tomimatsu-Sato solution
The physical properties of the Tomimatsu-Sato delta=2 spacetime are analyzed,
with emphasis on the issues of the negative mass distribution in this spacetime
and the origin of a massless ring singularity which are treated with the aid of
an equatorially asymmetric two-body configuration arising within the framework
of the analytically extended double-Kerr solution. As a by-product of this
analysis it is proved analytically that the Kerr spacetime with negative mass
always has a massless naked ring singularity off the symmetry axis accompanied
by a region with closed timelike curves, and it is also pointed out that the
Boyer-Lindquist coordinates in that case should be introduced in a different
manner than in the case of the Kerr solution with positive mass.Comment: 13 pages, 6 figures, submitted to Prog. Theor. Phy
On the Properties of Exact Solutions Endowed with Negative Mass
It is shown that various pathological properties of spacetimes can be
explained by the presence of negative mass, including the cases when the total
mass of the solution is a positive quantity. As an illustration, we consider
several well-known stationary axisymmetric vacuum and electrovac solutions of
the Einstein-Maxwell equations. Our investigation naturally leads to a critique
of the known maximal extensions of the Kerr and Kerr-Newman spacetimes which
turn out to be neither analytic nor physically meaningful.Comment: 4 pages, no figures; published versio
Determining parameters of the Neugebauer family of vacuum spacetimes in terms of data specified on the symmetry axis
We express the complex potential E and the metrical fields omega and gamma of
all stationary axisymmetric vacuum spacetimes that result from the application
of two successive quadruple-Neugebauer (or two double-Harrison) transformations
to Minkowski space in terms of data specified on the symmetry axis, which are
in turn easily expressed in terms of multipole moments. Moreover, we suggest
how, in future papers, we shall apply our approach to do the same thing for
those vacuum solutions that arise from the application of more than two
successive transformations, and for those electrovac solutions that have axis
data similar to that of the vacuum solutions of the Neugebauer family.
(References revised following response from referee.)Comment: 18 pages (REVTEX
Squeezed states of damped oscillator chain
The Caldirola-Kanai model of one-dimensional damped oscillator is extended to the chain of coupled parametric oscillators with damping. The correlated and squeezed states for the chain of coupled parametric oscillators with damping are constructed. Based on the concept of the integrals of motion, it is demonstrated how squeezing phenomenon arises due to parametric excitation
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