3,448 research outputs found
Black hole collisions from Brill-Lindquist initial data: predictions of perturbation theory
The Misner initial value solution for two momentarily stationary black holes
has been the focus of much numerical study. We report here analytic results for
an astrophysically similar initial solution, that of Brill and Lindquist (BL).
Results are given from perturbation theory for initially close holes and are
compared with available numerical results. A comparison is made of the
radiation generated from the BL and the Misner initial values, and the physical
meaning is discussed.Comment: 11 pages, revtex3.0, 5 figure
Choptuik scaling in null coordinates
A numerical simulation is performed of the gravitational collapse of a
spherically symmetric scalar field. The algorithm uses the null initial value
formulation of the Einstein-scalar equations, but does {\it not} use adaptive
mesh refinement. A study is made of the critical phenomena found by Choptuik in
this system. In particular it is verified that the critical solution exhibits
periodic self-similarity. This work thus provides a simple algorithm that gives
verification of the Choptuik results.Comment: latex (revtex), 6 figures included in the fil
The Evolution of Distorted Rotating Black Holes II: Dynamics and Analysis
We have developed a numerical code to study the evolution of distorted,
rotating black holes. This code is used to evolve a new family of black hole
initial data sets corresponding to distorted ``Kerr'' holes with a wide range
of rotation parameters, and distorted Schwarzschild black holes with odd-parity
radiation. Rotating black holes with rotation parameters as high as
are evolved and analyzed in this paper. The evolutions are generally carried
out to about , where is the ADM mass. We have extracted both the
even- and odd-parity gravitational waveforms, and find the quasinormal modes of
the holes to be excited in all cases. We also track the apparent horizons of
the black holes, and find them to be a useful tool for interpreting the
numerical results. We are able to compute the masses of the black holes from
the measurements of their apparent horizons, as well as the total energy
radiated and find their sum to be in excellent agreement with the ADM mass.Comment: 26 pages, LaTeX with RevTeX 3.0 macros. 27 uuencoded gz-compressed
postscript figures. Also available at http://jean-luc.ncsa.uiuc.edu/Papers/
Submitted to Physical Review
Properties of spin-triplet, even-parity superconductors
The physical consequences of the spin-triplet, even-parity pairing that has
been predicted to exist in disordered two-dimensional electron systems are
considered in detail. We show that the presence of an attractive interaction in
the particle-particle spin-triplet channel leads to an instability of the
normal metal that competes with the localizing effects of the disorder. The
instability is characterized by a diverging length scale, and has all of the
characteristics of a continuous phase transition. The transition and the
properties of the ordered phase are studied in mean-field theory, and by taking
into account Gaussian fluctuations. We find that the ordered phase is indeed a
superconductor with an ordinary Meissner effect and a free energy that is lower
than that of the normal metal. Various technical points that have given rise to
confusion in connection with this and other manifestations of odd-gap
superconductivity are also discussed.Comment: 15 pp., REVTeX, psfig, 2 ps figs, final version as publishe
Head--on Collision of Two Unequal Mass Black Holes
We present results from the first fully nonlinear numerical calculations of
the head--on collision of two unequal mass black holes. Selected waveforms of
the most dominant l=2, 3 and 4 quasinormal modes are shown, as are the total
radiated energies and recoil velocities for a range of mass ratios and initial
separations. Our results validate the close and distant separation limit
perturbation studies, and suggest that the head--on collision scenario is not
likely to produce an astrophysically significant recoil effect.Comment: 5 pages, 3 figure
Interactions and Scaling in a Disordered Two-Dimensional Metal
We show that a non-Fermi liquid state of interacting electrons in two
dimensions is stable in the presence of disorder and is a perfect conductor,
provided the interactions are sufficiently strong. Otherwise, the disorder
leads to localization as in the case of non-interacting electrons. This
conclusion is established by examining the replica field theory in the weak
disorder limit, but in the presence of arbitrary electron-electron interaction.
Thus, a disordered two-dimensional metal is a perfect metal, but not a Fermi
liquid.Comment: 4 pages, RevTe
An exact solution for 2+1 dimensional critical collapse
We find an exact solution in closed form for the critical collapse of a
scalar field with cosmological constant in 2+1 dimensions. This solution agrees
with the numerical simulation done by Pretorius and Choptuik of this system.Comment: 5 pages, 5 figures, Revtex. New comparison of analytic and numerical
solutions beyond the past light cone of the singularity added. Two new
references added. Error in equation (21) correcte
Scaling theory of two-dimensional metal-insulator transitions
We discuss the recently discovered two-dimensional metal-insulator transition
in zero magnetic field in the light of the scaling theory of localization. We
demonstrate that the observed symmetry relating conductivity and resistivity
follows directly from the quantum critical behavior associated with such a
transition. In addition, we show that very general scaling considerations imply
that any disordered two dimensional metal is a perfect metal, but most likely
not a Fermi liquid.Comment: 4 pages, no figures, REVTEX. Minor corrections adde
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