866 research outputs found
Bowen-York trumpet data and black-hole simulations
The most popular method to construct initial data for black-hole-binary
simulations is the puncture method, in which compactified wormholes are given
linear and angular momentum via the Bowen-York extrinsic curvature. When these
data are evolved, they quickly approach a ``trumpet'' topology, suggesting that
it would be preferable to use data that are in trumpet form from the outset. To
achieve this, we extend the puncture method to allow the construction of
Bowen-York trumpets, including an outline of an existence and uniqueness proof
of the solutions. We construct boosted, spinning and binary Bowen-York puncture
trumpets using a single-domain pseudospectral elliptic solver, and evolve the
binary data and compare with standard wormhole-data results. We also show that
for boosted trumpets the black-hole mass can be prescribed {\it a priori},
without recourse to the iterative procedure that is necessary for wormhole
data.Comment: 15 pages, 14 figures. Published versio
Implementation of standard testbeds for numerical relativity
We discuss results that have been obtained from the implementation of the
initial round of testbeds for numerical relativity which was proposed in the
first paper of the Apples with Apples Alliance. We present benchmark results
for various codes which provide templates for analyzing the testbeds and to
draw conclusions about various features of the codes. This allows us to sharpen
the initial test specifications, design a new test and add theoretical insight.Comment: Corrected versio
Beyond the Bowen-York extrinsic curvature for spinning black holes
It is well-known that Bowen-York initial data contain spurious radiation.
Although this ``junk'' radiation has been seen to be small for non-spinning
black-hole binaries in circular orbit, its magnitude increases when the black
holes are given spin. It is possible to reduce the spurious radiation by
applying the puncture approach to multiple Kerr black holes, as we demonstrate
for examples of head-on collisions of equal-mass black-hole binaries.Comment: 10 pages, 2 figures, submitted to special "New Frontiers in Numerical
Relativity" issue of Classical and Quantum Gravit
Retarded radiation from colliding black holes in the close limit
We use null hypersurface techniques in a new approach to calculate the retarded waveform from a binary black hole merger in the close approximation. The process of removing ingoing radiation from the system leads to two notable features in the shape of the close approximation waveform for a head-on collision of black holes: (i) an initial quasinormal ringup and (ii) weak sensitivity to the parameter controlling the collision velocity. Feature (ii) is unexpected and has the potential importance of enabling the design of an efficient template for extracting the gravitational wave signal from the noise
Total recoil: the maximum kick from nonspinning black-hole binary inspiral
When unequal-mass black holes merge, the final black hole receives a ``kick''
due to the asymmetric loss of linear momentum in the gravitational radiation
emitted during the merger. The magnitude of this kick has important
astrophysical consequences. Recent breakthroughs in numerical relativity allow
us to perform the largest parameter study undertaken to date in numerical
simulations of binary black hole inspirals. We study non-spinning black-hole
binaries with mass ratios from to (
from 0.25 to 0.16). We accurately calculate the velocity of the kick to within
6%, and the final spin of the black holes to within 2%. A maximum kick of
km s is achieved for .Comment: 4 pages, 4 figures. Version accepted by PR
Supermassive recoil velocities for binary black-hole mergers with antialigned spins
Recent calculations of the recoil velocity in binary black hole mergers have
found the kick velocity to be of the order of a few hundred km/s in the case of
non-spinning binaries and about km/s in the case of spinning
configurations, and have lead to predictions of a maximum kick of up to km/s. We test these predictions and demonstrate that kick velocities of at
least km/s are possible for equal-mass binaries with anti-aligned spins
in the orbital plane. Kicks of that magnitude are likely to have significant
repercussions for models of black-hole formation, the population of
intergalactic black holes and the structure of host galaxies.Comment: Final version, published by Phys. Rev. Lett.; title changed according
to suggestion of PRL; note added after preparation of manuscrip
Hyperboloidal evolution of test fields in three spatial dimensions
We present the numerical implementation of a clean solution to the outer
boundary and radiation extraction problems within the 3+1 formalism for
hyperbolic partial differential equations on a given background. Our approach
is based on compactification at null infinity in hyperboloidal scri fixing
coordinates. We report numerical tests for the particular example of a scalar
wave equation on Minkowski and Schwarzschild backgrounds. We address issues
related to the implementation of the hyperboloidal approach for the Einstein
equations, such as nonlinear source functions, matching, and evaluation of
formally singular terms at null infinity.Comment: 10 pages, 8 figure
Exploring black hole superkicks
Recent calculations of the recoil velocity in black-hole binary mergers have
found kick velocities of km/s for equal-mass binaries with
anti-aligned initial spins in the orbital plane. In general the dynamics of
spinning black holes can be extremely complicated and are difficult to analyze
and understand. In contrast, the ``superkick'' configuration is an example with
a high degree of symmetry that also exhibits exciting physics. We exploit the
simplicity of this ``test case'' to study more closely the role of spin in
black-hole recoil and find that: the recoil is with good accuracy proportional
to the difference between the modes of , the major
contribution to the recoil occurs within before and after the merger, and
that this is after the time at which a standard post-Newtonian treatment breaks
down. We also discuss consequences of the asymmetry in the
gravitational wave signal for the angular dependence of the SNR and the
mismatch of the gravitational wave signals corresponding to the north and south
poles
Impact of gravitational radiation higher order modes on single aligned-spin gravitational wave searches for binary black holes
Current template-based gravitational wave searches for compact binary coalescences (CBC) use waveform models that neglect the higher order modes content of the gravitational radiation emitted, considering only the quadrupolar modes. We study the effect of such a neglection for the case of aligned-spin CBC searches for equal-spin (and non-spinning) binary black holes in the context of two versions of Advanced LIGO: the upcoming 2015 version, known as early Advanced LIGO (eaLIGO) and its Zero-Detuned High Energy Power version, that we will refer to as Advanced LIGO (AdvLIGO). In addition, we study the case of a non-spinning search for initial LIGO (iLIGO). We do this via computing the effectualness of the aligned-spin SEOBNRv1 ROM waveform family, which only considers quadrupolar modes, towards hybrid post-Newtonian/Numerical Relativity waveforms which contain higher order modes. We find that for all LIGO versions, losses of more than of events occur for mass ratio and due to the neglection of higher modes. Moreover, for iLIGO and eaLIGO, losses notably increase up to respectively for the highest mass and mass ratio () studied. For the case of early AdvLIGO, losses of occur for and . Neglection of higher modes leads to observation-averaged systematic parameter biases towards lower spin, total mass and chirp mass. For completeness, we perform a preliminar, non-exhaustive comparison of systematic biases to statistical errors. We find that, for a given SNR, systematic biases dominate over statistical errors at much lower total mass for eaLIGO than for AdvLIGO
Gravitational waves from a fissioning white hole
We present a fully nonlinear calculation of the waveform of the gravitational radiation emitted in the fission of a vacuum white hole. At early times, the waveforms agree with close approximation perturbative calculations but they reveal dramatic time and angular dependence in the nonlinear regime. The results pave the way for a subsequent computation of the radiation emitted after a binary black hole merger
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