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Commit 6fcc8a20 authored by Duncan Meacher's avatar Duncan Meacher

Online pipelines: addressed minor comments

parent be41c8e5
Pipeline #55669 passed with stage
in 1 minute and 42 seconds
......@@ -23,16 +23,16 @@ mass BBH systems. However, GstLAL and PyCBC Live and SPIIR also include
intermediate-mass BBH systems and the O3 banks differ in detail from pipeline
to pipeline.
A coincident analysis is performed by GSTLAL, PyCBC Live, and MBTAOnline, where
candidate events are extracted separately at each detector via
matched-filtering and later combined across detectors. SPIIR extract candidates
of each detector via matched-filtering and look for coherent responses in other
detectors so that a sky localization of the source can be constructed. Of the
four pipelines, GstLAL and MBTAOnline use several banks of matched filters to
cover the detector bandwidth, i.e., the templates are split across multiple
frequency bands. All pipelines also implement different kinds of signal-based
vetoes to reject instrumental transients which cause large SNR values but can
otherwise be easily distinguished from compact binary coalescence signals.
A coincident analysis is performed by all pipelines, where candidate events are
extracted separately from each detector via matched-filtering and later
combined across detectors. SPIIR extracts candidates from each detector via
matched-filtering and looks for coherent responses from the other detectors to
provide source localization. Of the four pipelines, GstLAL and MBTAOnline use
several banks of matched filters to cover the detectors bandwidth, i.e., the
templates are split across multiple frequency bands. All pipelines also
implement different kinds of signal-based vetoes to reject instrumental
transients that cause large SNR values but can otherwise be easily
distinguished from compact binary coalescence signals.
**GSTLAL** [#GSTLAL1]_ [#GSTLAL2]_ is a matched-filter pipeline designed to
find gravitational waves from compact binaries in low-latency. It uses a
......@@ -41,13 +41,6 @@ rank candidates, and then uses Monte Carlo sampling methods to estimate the
distribution of likelihood-ratios in noise. This distribution can then be used
to compute a false alarm rate and p-value.
**SPIIR** [#SPIIR]_ [#SPIIRThesis]_ applies summed parallel infinite impulse
response (IIR) filters to approximate matched-filtering results. It selects
high-SNR events from each detector and find coherent responses from other
detectors. It constructs background by time-shifting detector data one hundred
times over a week to form a background statistic distribution used to evaluate
foreground candidate significance.
**MBTA** [#MBTA]_ constructs its background by making every possible
coincidence from single detector triggers over a few hours of recent data. It
then folds in the probability of a pair of triggers passing the time
......@@ -62,25 +55,33 @@ coincidences are recorded and assigned a ranking statistic; the false alarm
rate is then estimated by counting accidental coincidences louder than a given
candidate, i.e. with a higher statistic value.
**SPIIR** [#SPIIR]_ [#SPIIRThesis]_ applies summed parallel infinite impulse
response (IIR) filters to approximate matched-filtering results. It selects
high-SNR events from each detector and finds coherent responses from other
detectors. It constructs a background statistical distribution by time-shifting
detector data one hundred times over a week to evaluate foreground candidate
significance.
Unmodeled Search
----------------
**cWB** [#cWB]_ is an excess power algorithm to identify short-duration
gravitational wave-like signals. It uses a wavelet transformation to identify
time-frequency pixels which can be grouped in a single cluster if they satisfy
gravitational wave signals. It uses a wavelet transformation to identify
time-frequency pixels that can be grouped in a single cluster if they satisfy
neighboring conditions. A tuned version for compact-binary coalescences chooses
the time-frequency pixels if they mainly follow a pattern that increases in
frequency. A maximum-likelihood-statistics calculated over the cluster is used
to identify the proper parameter of the event, in particular the probability of
the source direction and the coherent network signal-to-noise ratio. The last
one is used to assign detection significance to the found events.
the source direction and the coherent network signal-to-noise ratio. The
largest likelihood value is used to assign detection significance to the found
events.
**oLIB** [#oLIB]_ uses the Q transform to decompose GW strain data into several
time-frequency planes of constant quality factors :math:`Q`, where :math:`Q
\sim \tau f_0`. The pipeline flags data segments containing excess power and
searches for clusters of these segments with identical :math:`f_0` and
:math:`Q` spaced within 100 ms of each other. Coincidences among the detector
network of clusters with a time-of-flight window up to 10 ms are then analyzed
network of clusters within a 10 ms light travel time window are then analyzed
with a coherent (i.e., correlated across the detector network) signal model to
identify possible GW candidate events.
......@@ -105,7 +106,7 @@ calculation to find joint GW+HEN triggers.
.. [#GSTLAL1]
Messick, C., Blackburn, K., Brady, P., et al. 2017, |prd|, 95, 042001.
https://doi.org/10.1103/PhysRevD.95.042001
.. [#GSTLAL2]
Sachdev, S., Caudill, S., Fong, H., et al. 2019, arXiv, 1901.08580.
https://arxiv.org/abs/1901.08580
......@@ -141,11 +142,11 @@ calculation to find joint GW+HEN triggers.
.. [#RAVEN]
Urban, A. L. 2016, Ph.D. Thesis.
http://adsabs.harvard.edu/abs/2016PhDT.........8U
.. [#LLAMA1]
Bartos, I., Veske, D., Keivani, A., et al. 2018, arXiv, 1810.11467.
https://arxiv.org/abs/1810.11467
.. [#LLAMA2]
Countryman, S., Keivani, A., Bartos, I., et al. 2019, arXiv, 1901.05486.
https://arxiv.org/abs/1901.05486
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