Autonomous gravitational-wave searches -- fully automated analyses of data that run without human intervention or assistance -- are desirable for a number of reasons. They are necessary for the rapid ...identification of gravitational-wave burst candidates, which in turn will allow for follow-up observations by other observatories and the maximum exploitation of their scientific potential. A fully automated analysis would also circumvent the traditional "by hand" setup and tuning of burst searches that is both labourious and time consuming. We demonstrate a fully automated search with X-Pipeline, a software package for the coherent analysis of data from networks of interferometers for detecting bursts associated with GRBs and other astrophysical triggers. We discuss the methods X-Pipeline uses for automated running, including background estimation, efficiency studies, unbiased optimal tuning of search thresholds, and prediction of upper limits. These are all done automatically via Monte Carlo with multiple independent data samples, and without requiring human intervention. As a demonstration of the power of this approach, we apply X-Pipeline to LIGO data to search for gravitational-wave emission associated with GRB 031108. We find that X-Pipeline is sensitive to signals approximately a factor of 2 weaker in amplitude than those detectable by the cross-correlation technique used in LIGO searches to date. We conclude with the prospects for running X-Pipeline as a fully autonomous, near real-time triggered burst search in the next LSC-Virgo Science Run.
The Advanced LIGO detectors are sophisticated opto-mechanical devices. At the core of their operation is feedback control. The Advanced LIGO project developed a custom digital control and data ...acquisition system to handle the unique needs of this new breed of astronomical detector. The advligortsis the software component of this system. This highly modular and extensible system has enabled the unprecedented performance of the LIGO instruments, and has been a vital component in the direct detection of gravitational waves.
► We estimate the gravitational-wave and high-energy neutrino emission window for GRBs. ► GRBs emit gravitational waves and high-energy neutrinos likely within 500
s. ► The derived time window allows ...for a 1000
s window in multimessenger searches. ► The analysis is largely based on model-motivated comparisons with observations.
We derive a conservative coincidence time window for joint searches of gravitational-wave (GW) transients and high-energy neutrinos (HENs, with energies ≳100
GeV), emitted by gamma-ray bursts (GRBs). The last are among the most interesting astrophysical sources for coincident detections with current and near-future detectors. We take into account a broad range of emission mechanisms. We take the upper limit of GRB durations as the 95% quantile of the
T
90’s of GRBs observed by BATSE, obtaining a GRB duration upper limit of ∼150
s. Using published results on high-energy (>100
MeV) photon light curves for 8 GRBs detected by Fermi LAT, we verify that most high-energy photons are expected to be observed within the first ∼150
s of the GRB. Taking into account the breakout-time of the relativistic jet produced by the central engine, we allow GW and HEN emission to begin up to 100
s before the onset of observable gamma photon production. Using published precursor time differences, we calculate a time upper bound for precursor activity, obtaining that 95% of precursors occur within ∼250
s prior to the onset of the GRB. Taking the above different processes into account, we arrive at a time window of
t
HEN
−
t
GW
∈
−500
s,
+500
s. Considering the above processes, an upper bound can also be determined for the expected time window of GW and/or HEN signals coincident with a detected GRB,
t
GW
−
t
GRB
≈
t
HEN
−
t
GRB
∈
−350
s,
+150
s. These upper bounds can be used to limit the coincidence time window in multimessenger searches, as well as aiding the interpretation of the times of arrival of measured signals.
The Laser Interferometer Gravitational-wave Observatory (LIGO) consists of two identical yet independent, widely-separated, long-baseline gravitational-wave detectors. Each Advanced LIGO detector ...consists of complex optical-mechanical systems isolated from the ground by multiple layers of active seismic isolation, all controlled by hundreds of fast, digital, feedback control systems. This article describes a novel state machine-based automation platform developed to handle the automation and supervisory control challenges of these detectors. The platform, called \textit{Guardian}, consists of distributed, independent, state machine automaton nodes organized hierarchically for full detector control. User code is written in standard Python and the platform is designed to facilitate the fast-paced development process associated with commissioning the complicated Advanced LIGO instruments. While developed specifically for the Advanced LIGO detectors, Guardian is a generic state machine automation platform that is useful for experimental control at all levels, from simple table-top setups to large-scale multi-million dollar facilities.
Gravitational waves produced at kilohertz frequencies in the aftermath of a neutron star collision can shed light on the behavior of matter at extreme temperatures and densities that are inaccessible ...to laboratory experiments. Gravitational-wave interferometers are limited by quantum noise at these frequencies but can be tuned via their optical configuration to maximize the probability of post-merger signal detection. We compare two such tuning strategies to turn Advanced LIGO into a post-merger-focused instrument: first, a wideband tuning that enhances the instrument's signal-to-noise ratio 40--80\% broadly above \SI{1}{\kHz} relative to the baseline, with a modest sensitivity penalty at lower frequencies; second, a "detuned" configuration that provides even more enhancement than the wideband tuning, but over only a narrow frequency band and at the expense of substantially worse quantum noise performance elsewhere. With an optimistic accounting for instrument loss and uncertainty in post-merger parameters, the detuned instrument has a \({\lesssim}40\%\) sensitivity improvement compared to the wideband instrument.
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