141 research outputs found
Quasinormal modes for massless topological black holes
An exact expression for the quasinormal modes of scalar perturbations on a
massless topological black hole in four and higher dimensions is presented. The
massive scalar field is nonminimally coupled to the curvature, and the horizon
geometry is assumed to have a negative constant curvature.Comment: CECS style, 11 pages, no figures. References adde
Area Spectrum of Extremal Reissner-Nordstr\"om Black Holes from Quasi-normal Modes
Using the quasi-normal modes frequency of extremal Reissner-Nordstr\"om black
holes, we obtain area spectrum for these type of black holes. We show that the
area and entropy black hole horizon are equally spaced. Our results for the
spacing of the area spectrum differ from that of schwarzschild black holes.Comment: 6 pages, no figure, accepted for publication in Phys. Rev.
Gravitational quasinormal radiation of higher-dimensional black holes
We find the gravitational resonance (quasinormal) modes of the higher
dimensional Schwarzschild and Reissner-Nordstrem black holes. The effect on the
quasinormal behavior due to the presence of the term is investigated.
The QN spectrum is totally different for different signs of . In more
than four dimensions there excited three types of gravitational modes: scalar,
vector, and tensor. They produce three different quasinormal spectra, thus the
isospectrality between scalar and vector perturbations, which takes place for
D=4 Schwarzschild and Schwarzschild-de-Sitter black holes, is broken in higher
dimensions. That is the scalar-type gravitational perturbations, connected with
deformations of the black hole horizon, which damp most slowly and therefore
dominate during late time of the black hole ringing.Comment: 13 pages, 2 figures, several references are adde
Dirac quasinormal modes of the Reissner-Nordstr\"om de Sitter black hole
The quasinormal modes of the Reissner-Nordstr\"om de Sitter black hole for
the massless Dirac fields are studied using the P\"oshl-Teller potential
approximation. We find that the magnitude of the imaginary part of the
quasinormal frequencies decreases as the cosmological constant or the orbital
angular momentum increases, but it increases as the charge or the overtone
number increases. An interesting feature is that the imaginary part is almost
linearly related to the real part as the cosmological constant changes for
fixed charge, and the linearity becomes better as the orbital angular momentum
increases. We also prove exactly that the Dirac quasinormal frequencies are the
same for opposite chirality.Comment: 10 pages, 6 figures, Phys. Rev. D in pres
Quasinormal behavior of the D-dimensional Schwarzshild black hole and higher order WKB approach
We study characteristic (quasinormal) modes of a -dimensional Schwarzshild
black hole. It proves out that the real parts of the complex quasinormal modes,
representing the real oscillation frequencies, are proportional to the product
of the number of dimensions and inverse horizon radius . The
asymptotic formula for large multipole number and arbitrary is derived.
In addition the WKB formula for computing QN modes, developed to the 3rd order
beyond the eikonal approximation, is extended to the 6th order here. This gives
us an accurate and economic way to compute quasinormal frequencies.Comment: 15 pages, 6 figures, the 6th order WKB formula for computing QNMs in
Mathematica is available from https://goo.gl/nykYG
Quasinormal modes of Schwarzschild black holes in four and higher dimensions
We make a thorough investigation of the asymptotic quasinormal modes of the
four and five-dimensional Schwarzschild black hole for scalar, electromagnetic
and gravitational perturbations. Our numerical results give full support to all
the analytical predictions by Motl and Neitzke, for the leading term. We also
compute the first order corrections analytically, by extending to higher
dimensions, previous work of Musiri and Siopsis, and find excellent agreement
with the numerical results. For generic spacetime dimension number D the
first-order corrections go as . This means that
there is a more rapid convergence to the asymptotic value for the five
dimensional case than for the four dimensional case, as we also show
numerically.Comment: 12 pages, 5 figures, RevTeX4. v2. Typos corrected, references adde
Fabrication of CuO nanoparticle interlinked microsphere cages by solution method
Here we report a very simple method to convert conventional CuO powders to nanoparticle interlinked microsphere cages by solution method. CuO is dissolved into aqueous ammonia, and the solution is diluted by alcohol and dip coating onto a glass substrate. Drying at 80 °C, the nanostructures with bunchy nanoparticles of Cu(OH)2can be formed. After the substrate immerges into the solution and we vaporize the solution, hollow microspheres can be formed onto the substrate. There are three phases in the as-prepared samples, monoclinic tenorite CuO, orthorhombic Cu(OH)2, and monoclinic carbonatodiamminecopper(II) (Cu(NH3)2CO3). After annealing at 150 °C, the products convert to CuO completely. At annealing temperature above 350 °C, the hollow microspheres became nanoparticle interlinked cages
Quasinormal frequencies of Schwarzschild black holes in anti-de Sitter spacetimes: A complete study on the asymptotic behavior
We present a thorough analysis for the quasinormal (QN) behavior, associated
with the decay of scalar, electromagnetic and gravitational perturbations, of
Schwarzschild-anti-de Sitter black holes. As it is known the anti-de Sitter
(AdS) QN spectrum crucially depends on the relative size of the black hole to
the AdS radius. There are three different types of behavior depending on
whether the black hole is large, intermediate, or small. The results of
previous works, concerning lower overtones for large black holes, are completed
here by obtaining higher overtones for all the three black hole regimes. There
are two major conclusions that one can draw from this work: First,
asymptotically for high overtones, all the modes are evenly spaced, and this
holds for all three types of regime, large, intermediate and small black holes,
independently of l, where l is the quantum number characterizing the angular
distribution; Second, the spacing between modes is apparently universal, in
that it does not depend on the field, i.e., scalar, electromagnetic and
gravitational QN modes all have the same spacing for high overtones. We are
also able to prove why scalar and gravitational perturbations are isospectral,
asymptotically for high overtones, by introducing appropriate superpartner
potentials.Comment: 22 page
The Majorana Neutrinoless Double-Beta Decay Experiment
The proposed Majorana double-beta decay experiment is based on an array of
segmented intrinsic Ge detectors with a total mass of 500 kg of Ge isotopically
enriched to 86% in 76Ge. A discussion is given of background reduction by:
material selection, detector segmentation, pulse shape analysis, and
electro-formation of copper parts and granularity. Predictions of the
experimental sensitivity are given. For an experimental running time of 10
years over the construction and operation of Majorana, a half-life sensitivity
of ~4x10^27 y (neutrinoless) is predicted. This corresponds to an effective
Majorana mass of the electron neutrino of ~0.03-0.04 eV, according to recent
QRPA and RQRPA matrix element calculations.Comment: 10 pages, 7 figure
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