6,574 research outputs found
The Final Remnant of Binary Black Hole Mergers: Multipolar Analysis
Methods are presented to define and compute source multipoles of dynamical
horizons in numerical relativity codes, extending previous work from the
isolated and dynamical horizon formalisms in a manner that allows for the
consideration of horizons that are not axisymmetric. These methods are then
applied to a binary black hole merger simulation, providing evidence that the
final remnant is a Kerr black hole, both through the (spatially)
gauge-invariant recovery of the geometry of the apparent horizon, and through a
detailed extraction of quasinormal ringing modes directly from the strong-field
region.Comment: 12 pages, 13 figures. Published version. Some references have been
added and reordered, and the figures cleaned up
ANTIQUITIES OF BAIL: ORIGIN AND HISTORICAL DEVELOPMENT IN CRIMINAL CASES TO THE YEAR 1275, by Elsa de Haas. Columbia University Press, New York, 1940. Pp. xii, 174.
Tidal coupling of a Schwarzschild black hole and circularly orbiting moon
We describe the possibility of using LISA's gravitational-wave observations
to study, with high precision, the response of a massive central body to the
tidal gravitational pull of an orbiting, compact, small-mass object. Motivated
by this application, we use first-order perturbation theory to study tidal
coupling for an idealized case: a massive Schwarzschild black hole, tidally
perturbed by a much less massive moon in a distant, circular orbit. We
investigate the details of how the tidal deformation of the hole gives rise to
an induced quadrupole moment in the hole's external gravitational field at
large radii. In the limit that the moon is static, we find, in Schwarzschild
coordinates and Regge-Wheeler gauge, the surprising result that there is no
induced quadrupole moment. We show that this conclusion is gauge dependent and
that the static, induced quadrupole moment for a black hole is inherently
ambiguous. For the orbiting moon and the central Schwarzschild hole, we find
(in agreement with a recent result of Poisson) a time-varying induced
quadrupole moment that is proportional to the time derivative of the moon's
tidal field. As a partial analog of a result derived long ago by Hartle for a
spinning hole and a stationary distant companion, we show that the orbiting
moon's tidal field induces a tidal bulge on the hole's horizon, and that the
rate of change of the horizon shape leads the perturbing tidal field at the
horizon by a small angle.Comment: 14 pages, 0 figures, submitted to Phys. Rev.
Computing the merger of black-hole binaries: the IBBH problem
Gravitational radiation arising from the inspiral and merger of binary black
holes (BBH's) is a promising candidate for detection by kilometer-scale
interferometric gravitational wave observatories. This paper discusses a
serious obstacle to searches for such radiation and to the interpretation of
any observed waves: the inability of current computational techniques to evolve
a BBH through its last ~10 orbits of inspiral (~100 radians of
gravitational-wave phase). A new set of numerical-relativity techniques is
proposed for solving this ``Intermediate Binary Black Hole'' (IBBH) problem:
(i) numerical evolutions performed in coordinates co-rotating with the BBH, in
which the metric coefficients evolve on the long timescale of inspiral, and
(ii) techniques for mathematically freezing out gravitational degrees of
freedom that are not excited by the waves.Comment: 6 pages RevTe
In-Chain Tunneling Through Charge-Density Wave Nanoconstrictions and Break-Junctions
We have fabricated longitudinal nanoconstrictions in the charge-density wave
conductor (CDW) NbSe using a focused ion beam and using a mechanically
controlled break-junction technique. Conductance peaks are observed below the
TK and TK CDW transitions, which correspond closely
with previous values of the full CDW gaps and
obtained from photo-emission. These results can be explained by assuming
CDW-CDW tunneling in the presence of an energy gap corrugation
comparable to , which eliminates expected peak at
. The nanometer length-scales our experiments imply
indicate that an alternative explanation based on tunneling through
back-to-back CDW-normal junctions is unlikely.Comment: 5 pages, 3 figures, submitted to physical review letter
Effects of cryoprotectant concentration and cooling rate on vitrification of aqueous solutions
Vitrification of aqueous cryoprotectant mixtures is essential in
cryopreservation of proteins and other biological samples. We report systematic
measurements of critical cryoprotective agent (CPA) concentrations required for
vitrification during plunge cooling from T=295 K to T=77 K in liquid nitrogen.
Measurements on fourteen common CPAs including alcohols (glycerol, methanol,
isopropanol), sugars (sucrose, xylitol, dextrose, trehalose), PEGs (ethylene
glycol, PEG 200, PEG 2 000, PEG 20 000), glycols (DMSO, MPD), and salt (NaCl)
were performed for volumes ranging over four orders of magnitude from ~nL to 20
mkL, and covering the range of interest in protein crystallography. X-ray
diffraction measurements on aqueous glycerol mixtures confirm that the
polycrystalline-to-vitreous transition occurs within a span of less than 2% w/v
in CPA concentration, and that the form of polycrystalline ice (hexagonal or
cubic) depends on CPA concentration and cooling rate. For most of the studied
cryoprotectants, the critical concentration decreases strongly with volume in
the range from ~5 mkL to ~0.1 mkL, typically by a factor of two. By combining
measurements of the critical concentration versus volume with cooling time
versus volume, we obtain the function of greatest intrinsic physical interest:
the critical CPA concentration versus cooling rate during flash cooling. These
results provide a basis for more rational design of cryoprotective protocols,
and should yield insight into the physics of glass formation in aqueous
mixtures.Comment: 8 pages, 6 jpg figure, 2 table
Central Exclusive Di-jet Production at the Tevatron
We perform a phenomenological analysis of dijet production in double pomeron
exchange at the Tevatron. We find that the CDF Run I results do not rule out
the presence of an exclusive dijet component, as predicted by Khoze, Martin and
Ryskin (KMR). With the high statistics CDF Run II data, we predict that an
exclusive component at the level predicted by KMR may be visible, although the
observation will depend on accurate modelling of the inclusive double pomeron
exchange process. We also compare to the predictions of the DPEMC Monte Carlo,
which contains a non-perturbative model for the central exclusive process. We
show that the perturbative model of KMR gives different predictions for the
di-jet ET dependence in the high di-jet mass fraction region than
non-perturbative models.Comment: 17 pages, 15 figure
Distortion of Schwarzschild-anti-de Sitter black holes to black strings
Motivated by the existence of black holes with various topologies in
four-dimensional spacetimes with a negative cosmological constant, we study
axisymmetric static solutions describing any large distortions of
Schwarzschild-anti-de Sitter black holes parametrized by the mass . Under
the approximation such that is much larger than the anti-de Sitter radius,
it is found that a cylindrically symmetric black string is obtained as a
special limit of distorted spherical black holes. Such a prolonged distortion
of the event horizon connecting a Schwarzschild-anti-de Sitter black hole to a
black string is allowed without violating both the usual black hole
thermodynamics and the hoop conjecture for the horizon circumference.Comment: 13 pages, accepted for publication in Physical Review
Regularization of second-order scalar perturbation produced by a point-particle with a nonlinear coupling
Accurate calculation of the motion of a compact object in a background
spacetime induced by a supermassive black hole is required for the future
detection of such binary systems by the gravitational-wave detector LISA.
Reaching the desired accuracy requires calculation of the second-order
gravitational perturbations produced by the compact object. At the point
particle limit the second-order gravitational perturbation equations turn out
to have highly singular source terms, for which the standard retarded solutions
diverge. Here we study a simplified scalar toy-model in which a point particle
induces a nonlinear scalar field in a given curved spacetime. The corresponding
second-order scalar perturbation equation in this model is found to have a
similar singular source term, and therefore its standard retarded solutions
diverge. We develop a regularization method for constructing well-defined
causal solutions for this equation. Notably these solutions differ from the
standard retarded solutions, which are ill-defined in this case.Comment: 14 page
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