13,692 research outputs found
Reducing the number of templates for aligned-spin compact binary coalescence gravitational wave searches using metric-agnostic template nudging
Efficient multi-dimensional template placement is crucial in computationally
intensive matched-filtering searches for Gravitational Waves (GWs). Here, we
implement the Neighboring Cell Algorithm (NCA) to improve the detection volume
of an existing Compact Binary Coalescence (CBC) template bank. This algorithm
has already been successfully applied for a binary millisecond pulsar search in
data from the Fermi satellite. It repositions templates from over-dense regions
to under-dense regions and reduces the number of templates that would have been
required by a stochastic method to achieve the same detection volume. Our
method is readily generalizable to other CBC parameter spaces. Here we apply
this method to the aligned--single-spin neutron-star--black-hole binary
coalescence inspiral-merger-ringdown gravitational wave parameter space. We
show that the template nudging algorithm can attain the equivalent
effectualness of the stochastic method with 12% fewer templates
Improved Stack-Slide Searches for Gravitational-Wave Pulsars
We formulate and optimize a computational search strategy for detecting
gravitational waves from isolated, previously-unknown neutron stars (that is,
neutron stars with unknown sky positions, spin frequencies, and spin-down
parameters). It is well known that fully coherent searches over the relevant
parameter-space volumes are not computationally feasible, and so more
computationally efficient methods are called for. The first step in this
direction was taken by Brady & Creighton (2000), who proposed and optimized a
two-stage, stack-slide search algorithm. We generalize and otherwise improve
upon the Brady-Creighton scheme in several ways. Like Brady & Creighton, we
consider a stack-slide scheme, but here with an arbitrary number of
semi-coherent stages and with a coherent follow-up stage at the end. We find
that searches with three semi-coherent stages are significantly more efficient
than two-stage searches (requiring about 2-5 times less computational power for
the same sensitivity) and are only slightly less efficient than searches with
four or more stages. We calculate the signal-to-noise ratio required for
detection, as a function of computing power and neutron star spin-down-age,
using our optimized searches.Comment: 19 pages, 7 figures, RevTeX
Search strategies for long gravitational-wave transients: hidden Markov model tracking and seedless clustering
A number of detections have been made in the past few years of gravitational
waves from compact binary coalescences. While there exist well-understood
waveform models for signals from compact binary coalescences, many sources of
gravitational waves are not well modeled, including potential long-transient
signals from a binary neutron star post-merger remnant. Searching for these
sources requires robust detection algorithms that make minimal assumptions
about any potential signals. In this paper, we compare two unmodeled search
schemes for long-transient gravitational waves, operating on cross-power
spectrograms. One is an efficient algorithm first implemented for continuous
wave searches, based on a hidden Markov model. The other is a seedless
clustering method, which has been used in transient gravitational wave analysis
in the past. We quantify the performance of both algorithms, including
sensitivity and computational cost, by simulating synthetic signals with a
special focus on sources like binary neutron star post-merger remnants. We
demonstrate that the hidden Markov model tracking is a good option in
model-agnostic searches for low signal-to-noise ratio signals. We also show
that it can outperform the seedless method for certain categories of signals
while also being computationally more efficient.Comment: 10 pages, 7 figure
An all-sky search algorithm for continuous gravitational waves from spinning neutron stars in binary systems
Rapidly spinning neutron stars with non-axisymmetric mass distributions are
expected to generate quasi-monochromatic continuous gravitational waves. While
many searches for unknown, isolated spinning neutron stars have been carried
out, there have been no previous searches for unknown sources in binary
systems. Since current search methods for unknown, isolated neutron stars are
already computationally limited, expanding the parameter space searched to
include binary systems is a formidable challenge. We present a new hierarchical
binary search method called TwoSpect, which exploits the periodic orbital
modulations of the continuous waves by searching for patterns in doubly
Fourier-transformed data. We will describe the TwoSpect search pipeline,
including its mitigation of detector noise variations and corrections for
Doppler frequency modulation caused by changing detector velocity. Tests on
Gaussian noise and on a set of simulated signals will be presented.Comment: 22 pages, 10 figures, 1 table, Submitted to Classical and Quantum
Gravit
The PyCBC search for gravitational waves from compact binary coalescence
We describe the PyCBC search for gravitational waves from compact-object
binary coalescences in advanced gravitational-wave detector data. The search
was used in the first Advanced LIGO observing run and unambiguously identified
two black hole binary mergers, GW150914 and GW151226. At its core, the PyCBC
search performs a matched-filter search for binary merger signals using a bank
of gravitational-wave template waveforms. We provide a complete description of
the search pipeline including the steps used to mitigate the effects of noise
transients in the data, identify candidate events and measure their statistical
significance. The analysis is able to measure false-alarm rates as low as one
per million years, required for confident detection of signals. Using data from
initial LIGO's sixth science run, we show that the new analysis reduces the
background noise in the search, giving a 30% increase in sensitive volume for
binary neutron star systems over previous searches.Comment: 29 pages, 7 figures, accepted by Classical and Quantum Gravit
Gravitational waves: search results, data analysis and parameter estimation
The Amaldi 10 Parallel Session C2 on gravitational wave (GW) search results, data analysis and parameter estimation included three lively sessions of lectures by 13 presenters, and 34 posters. The talks and posters covered a huge range of material, including results and analysis techniques for ground-based GW detectors, targeting anticipated signals from different astrophysical sources: compact binary inspiral, merger and ringdown; GW bursts from intermediate mass binary black hole mergers, cosmic string cusps, core-collapse supernovae, and other unmodeled sources; continuous waves from spinning neutron stars; and a stochastic GW background. There was considerable emphasis on Bayesian techniques for estimating the parameters of coalescing compact binary systems from the gravitational waveforms extracted from the data from the advanced detector network. This included methods to distinguish deviations of the signals from what is expected in the context of General Relativity
A stochastic template placement algorithm for gravitational wave data analysis
This paper presents an algorithm for constructing matched-filter template
banks in an arbitrary parameter space. The method places templates at random,
then removes those which are "too close" together. The properties and
optimality of stochastic template banks generated in this manner are
investigated for some simple models. The effectiveness of these template banks
for gravitational wave searches for binary inspiral waveforms is also examined.
The properties of a stochastic template bank are then compared to the
deterministically placed template banks that are currently used in
gravitational wave data analysis.Comment: 14 pages, 11 figure
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