11 research outputs found
pygwb: Python-based library for gravitational-wave background searches
The collection of gravitational waves (GWs) that are either too weak or too
numerous to be individually resolved is commonly referred to as the
gravitational-wave background (GWB). A confident detection and model-driven
characterization of such a signal will provide invaluable information about the
evolution of the Universe and the population of GW sources within it. We
present a new, user-friendly Python--based package for gravitational-wave data
analysis to search for an isotropic GWB in ground--based interferometer data.
We employ cross-correlation spectra of GW detector pairs to construct an
optimal estimator of the Gaussian and isotropic GWB, and Bayesian parameter
estimation to constrain GWB models. The modularity and clarity of the code
allow for both a shallow learning curve and flexibility in adjusting the
analysis to one's own needs. We describe the individual modules which make up
{\tt pygwb}, following the traditional steps of stochastic analyses carried out
within the LIGO, Virgo, and KAGRA Collaboration. We then describe the built-in
pipeline which combines the different modules and validate it with both mock
data and real GW data from the O3 Advanced LIGO and Virgo observing run. We
successfully recover all mock data injections and reproduce published results.Comment: 32 pages, 14 figure
Gravitational-Wave Geodesy: Defining False Alarm Probabilities with Respect to Correlated Noise
Future searches for a gravitational-wave background using Earth-based
gravitational-wave detectors might be impacted by correlated noise sources. A
well known example are the Schumann resonances, which are extensively studied
in the context of searches for a gravitational-wave background. Earlier work
has shown that a technique termed "gravitational-wave geodesy" can be used to
generically differentiate observations of a gravitational-wave background from
signals due to correlated terrestrial effects, requiring true observations to
be consistent with the known geometry of our detector network. The key result
of this test is a Bayes factor between the hypotheses that a candidate signal
is astrophysical or terrestrial in origin. Here, we further formalize the
geodesy test, mapping distributions of false-alarm and false-acceptance
probabilities to quantify the degree with which a given Bayes factor will boost
or diminish our confidence in an apparent detection of the gravitational-wave
background. To define the false alarm probability of a given Bayes factor, we
must have knowledge of our null hypothesis: the space of all possible
correlated terrestrial signals. Since we do not have this knowledge we instead
construct a generic space of smooth functions in the frequency domain using
Gaussian processes, which we tailor to be conservative. This enables us to use
draws from our Gaussian processes as a proxy for all possible non-astrophysical
signals. As a demonstration, we apply the tool to the SNR = 1.25 excess
observed for a 2/3-power law by the LIGO and Virgo collaborations during their
second observing run
Measurement of the Cross-Correlation Angular Power Spectrum Between the Stochastic Gravitational Wave Background and Galaxy Over-Density
International audienceWe study the cross-correlation between the stochastic gravitational-wave background (SGWB) generated by binary black hole (BBH) mergers across the universe and the distribution of galaxies across the sky. We use the anisotropic SGWB measurement obtained using data from the third observing run (O3) of Advanced LIGO detectors and galaxy over-density obtained from the Sloan Digital Sky Survey (SDSS) spectroscopic catalog. We compute, for the first time, the angular power spectrum of their cross-correlation. Instead of integrating the SGWB across frequencies, we analyze the cross-correlation in 10 Hz wide SGWB frequency bands to study the frequency dependence of the cross-correlation angular power spectrum. Finally, we compare the observed cross-correlation to the spectra predicted by astrophysical models. We apply a Bayesian formalism to explore the parameter space of the theoretical models, and we set constraints on a set of (effective) astrophysical parameters describing the galactic process of gravitational wave (GW) emission. Parameterizing with a Gaussian function the astrophysical kernel describing the local process of GW emission at galactic scales, we find the 95% upper limit on kernel amplitude to be erg cms when ignoring the shot noise in the GW emission process, and erg cms when the shot noise is included in the analysis. As the sensitivity of the LIGO-Virgo-KAGRA network improves, we expect to be able to set more stringent bounds on this kernel function and constrain its parameters
2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European respiratory society (ERS) : The Task Force for the diagnosis and management of acute pulmonary embolism of the European Society of Cardiology (ESC)
Guidelines summarize and evaluate available evidence with the aim of assisting health professionals in proposing the best management strategies for an individual patient with a given condition. Guidelines and their recommendations should facilitate decision making of health professionals in their daily practice. However, the final decisions concerning an individual patient must be made by the responsible health professional(s) in consultation with the patient and caregiver as appropriate
2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society (ERS).
Guidelines summarize and evaluate available evidence with the aim of assisting health professionals in proposing the best management strategies for an individual patient with a given condition. Guidelines and their recommendations should facilitate decision making of health professionals in their daily practice. However, the final decisions concerning an individual patient must be made by the responsible health professional(s) in consultation with the patient and caregiver as appropriate
2019 ESC guidelines for the dignosis and management of acute pulmonary embolism developed in collaboration with the european respiratory society (ERS)
Guidelines summarize and evaluate available evidence with the aim of assisting health professionals in proposing the best management strategies for an individual patient with a given condition. Guidelines and their recommendations should facilitate decision making of health professionals in their daily practice. However, the final decisions concerning an individual patient must be made by the responsible health professional(s) in consultation with the patient and caregiver as appropriate
Open data from the first and second observing runs of Advanced LIGO and Advanced Virgo
Advanced LIGO and Advanced Virgo are monitoring the sky and collecting gravitational-wave strain data with sufficient sensitivity to detect signals routinely. In this paper we describe the data recorded by these instruments during their first and second observing runs. The main data products are gravitational-wave strain time series sampled at 16384 Hz. The datasets that include this strain measurement can be freely accessed through the Gravitational Wave Open Science Center at http://gw-openscience.org, together with data-quality information essential for the analysis of LIGO and Virgo data, documentation, tutorials, and supporting software