Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Comparing Gravitational Waveform Extrapolation to Cauchy-Characteristic
  Extraction in Binary Black Hole Simulations   We extract gravitational waveforms from numerical simulations of black hole
binaries computed using the Spectral Einstein Code. We compare two extraction
methods: direct construction of the Newman-Penrose (NP) scalar $\Psi_4$ at a
finite distance from the source and Cauchy-characteristic extraction (CCE). The
direct NP approach is simpler than CCE, but NP waveforms can be contaminated by
near-zone effects---unless the waves are extracted at several distances from
the source and extrapolated to infinity. Even then, the resulting waveforms can
in principle be contaminated by gauge effects. In contrast, CCE directly
provides, by construction, gauge-invariant waveforms at future null infinity.
We verify the gauge invariance of CCE by running the same physical simulation
using two different gauge conditions. We find that these two gauge conditions
produce the same CCE waveforms but show differences in extrapolated-$\Psi_4$
waveforms. We examine data from several different binary configurations and
measure the dominant sources of error in the extrapolated-$\Psi_4$ and CCE
waveforms. In some cases, we find that NP waveforms extrapolated to infinity
agree with the corresponding CCE waveforms to within the estimated error bars.
However, we find that in other cases extrapolated and CCE waveforms disagree,
most notably for $m=0$ "memory" modes.

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The categories of this paper are: nucl-th
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The categories of this paper are: cs
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The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: q-fin
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The categories of this paper are: chao-dyn
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The categories of this paper are: mtrl-th
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The categories of this paper are: stat
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The categories of this paper are: ao-sci
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The categories of this paper are: econ
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The categories of this paper are: math-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-th
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The categories of this paper are: math
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-ex