4,092 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
Cosmological dynamics in tomographic probability representation
The probability representation for quantum states of the universe in which
the states are described by a fair probability distribution instead of wave
function (or density matrix) is developed to consider cosmological dynamics.
The evolution of the universe state is described by standard positive
transition probability (tomographic transition probability) instead of the
complex transition probability amplitude (Feynman path integral) of the
standard approach. The latter one is expressed in terms of the tomographic
transition probability. Examples of minisuperspaces in the framework of the
suggested approach are presented. Possibility of observational applications of
the universe tomographs are discussed.Comment: 16 page
On the physical parametrization and magnetic analogs of the Emparan-Teo dihole solution
The Emparan-Teo non-extremal black dihole solution is reparametrized using
Komar quantities and the separation distance as arbitrary parameters. We show
how the potential can be calculated for the magnetic analogs of this
solution in the Einstein-Maxwell and Einstein-Maxwell-dilaton theories. We also
demonstrate that, similar to the extreme case, the external magnetic field can
remove the supporting strut in the non-extremal black dihole too.Comment: 9 pages, 1 figur
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
Tomographic entropy and cosmology
The probability representation of quantum mechanics including propagators and
tomograms of quantum states of the universe and its application to quantum
gravity and cosmology are reviewed. The minisuperspaces modeled by oscillator,
free pointlike particle and repulsive oscillator are considered. The notion of
tomographic entropy and its properties are used to find some inequalities for
the tomographic probability determining the quantum state of the universe. The
sense of the inequality as a lower bound for the entropy is clarified.Comment: 19 page
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
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