Transcript Inspiral Group Report: S1 Preliminary Report

LIGO Data Analysis: Status and Plans
Patrick Brady
University of Wisconsin-Milwaukee
LIGO Scientific Collaboration
Outline of talk
• First LIGO science data run (S1)
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Summary of run
Organization of LIGO data analysis efforts
Status of each effort
Detailed discussion of burst/inspiral analysis
– Emphasis because of TAMA/LIGO coincidence analysis
• Plans for second LIGO science data run (S2)
» Online analysis plans/status
» Tools used in control room
• Summary
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LIGO Run Schedule
• Science runs are interspersed with engineering runs
and commissioning activities
10-18
10-19
Nov
S3
Now
E10,…
Oct
Sep
Aug
S2
Jul
Jun
May
Apr
E9
strain noise per root Hz
Mar
Feb
Jan 2003
S1
Dec
Nov
E8
10-21
Oct
Sep
Aug
Jul
Jun
May
Apr
Mar
Feb
Jan 2002
E7
10-20
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LIGO sensitivity at start of S1
• S1 run
» 23 Aug – 9 Sep, 2002
• Standard candle
» 2 x 1.4 Msun optimally
oriented binary
• S1 reach includes
» Milky Way
» LMC
» SMC
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Data from S1 run
H1: 235 Hours
H2: 298 Hours
L1: 170 Hours
3x: 95.7 Hours
• S1 total run time: 408 hours = 17 days
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H1 (4km, Hanford) – duty cycle 57.6%
H2 (2km, Hanford) – duty cycle 73.1%
L1 (4km, Livingston) – duty cycle 41.7%
Triple coincidence – duty cycle 23.4%
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Green bands with
black borders indicate
locked segments
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Data analysis groups
• Burst and other transients:
» Sam Finn and Peter Saulson (co-chairs)
» http://www.ligo.caltech.edu/~ajw/bursts/bursts.html
• Continuous Wave
» Michael Landry and Mariallessandra Papa (co-chairs)
» http://www.lsc-group.phys.uwm.edu/pulgroup/
• Inspiral
» Patrick Brady and Gabriel Gonzalez (co-chairs)
» http://www.lsc-group.phys.uwm.edu/iulgroup/
• Stochastic
» Peter Fritschel and Joe Romano (co-chairs)
» http://feynman.utb.edu/~joe/research/stochastic/upperlimits
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Burst Group Activities
• Search for bursts of unknown origin/waveform
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Generate event triggers using SLOPE, TFCLUSTERS, POWER
Veto triggers due to instrumental artifacts
Determine upper limit on rate as function of strain
Monte Carlo by simulated injections of astrophysical motivated
signals (Zwerger et al) and other burst waveforms
• Search for bursts associated with GRB’s.
» Triggered analysis of on-source times
» Result by comparison of on-source versus off-source distributions
» First EM triggered search with LIGO
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Continuous Wave Group Analysis
• Known pulsar searches
» Catalog of known pulsars
» Heterodyne narrow BW folding data
» Coherent frequency domain search using Hough transform
• All sky unbiased
» Sum short power spectra (no doppler correction)
• Wide area search
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Hierarchical Hough transform code is under development
Demodulation is functioning and used in known pulsar search
Demodulation points on sky under control
Efficient positioning of spindown/sky points under development
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Inspiral Group Activities
• Binary Neutron Star Search
» Bread ‘n butter source for LIGO
» Determined upper limit on the rate of BNS inspirals in the universe
• Black hole MACHO binary search (0.5<m1,m2<1.0)
» Speculative source
» MACHO search will use same pipeline as BNS
» Unbiased search and upper limit will follow neutron star result
• Binary black hole search (m1,m2 > 3.0 Msun)
» An unbiased search will not be made due to proximity of S2
» Will use the full S1 data set to explore techniques for S2
» Need to better understand veto strategies for BBH
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Stochastic Group Activities
• Analytic calculation of expected upper limits (~100 hrs):
 W for LHO 2k-LHO 4k will provide the most stringent direct
observational upper limit to date
• Coherence measurements of GW channels show little
coherence for LLO-LHO 2k correlations
• Investigation of effect of line removal for LHO 2km-LHO 4km
correlations (e.g., reduction in instrumental correlated noise)
• Injection of simulated stochastic signals into the data and
extraction from the noise to validate end-to-end capability of
analysis
• Correlations between LLO with ALLEGRO bar detector
» ALLEGRO was rotated into 3 different positions during earlier E7 run
» Analysis in progress
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Playground Data Set
• Representative sample of data distributed over run
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Not used in determining astrophysical results
Used to tune thresholds
Determine veto cuts
Gain experience without introducing bias into upper limit analyses
• Characteristics
» ~9 hours of triple coincident data was selected for this purpose
» Chosen by Gabriela Gonzalez in consultation with others on site
» Representative of broad range of instrumental behavior
• Which groups used it?
» Inspiral group
» Burst group
» Stochastic group
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Burst Trigger Generation
• One hour summary plot
• Confidence
» Log( probability that trigger is
caused by Gaussian noise)
» Large negative value is loud
burst
• Time-frequency plot
» Green: 0 > confidence > -100
» Red: confidence < -100
• No. of events
» Triggers per 10 seconds
• Event definition
Trigger in 200-400Hz band with
duration ~100 sec
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» Different for TFCLUSTER,
SLOPE, POWER
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Inspiral Trigger Generation: Templates
• Use template based matched
filtering algorithm
• Template waveforms for nonspinning binaries
» 2.0 post-Newtonian approx.
• Computational efficiency
» Stationary phase approximation
to Fourier Transform
• Discrete set of templates labeled
by M1, M2
» 1.0 Msun < m1, m2 < 3.0 Msun
» 2110 templates
» At most 3% loss in SNR
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Inspiral Trigger Generation
• AS_Q processed in chunks of 256 seconds down-sampled
to 4096Hz
• Each chunk is divided into 7 segments of 64 seconds
overlapped by 32 seconds
• For each template:
» Compute the SNR: large values indicate that GW channel correlates well
with the template
» If SNR > 6.5, compute a2 : small values indicate that SNR was
accumulated in a manner consistent with an inspiral signal.
» If a2 < 5.0, record trigger
» Triggers are clustered within duration of each template, but multiple
templates can trigger at same time.
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Dealing with Non-Gaussian Spurions
• Example at LIGO Louisianna
» Cattle Guard
» (Gonzalez, Chickarmane,
Saulson during E7)
• How to deal with them?
» Auxiliary channels vetoes
» Can physical cause be tracked?
• Use PEM & other channels
» Potential vetoes
» Evaluated vetoes generated by
several tools
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Veto Investigations
• Tuned veto SNR thresholds and “windows” using the
playground data; focused on eliminating the highest-SNR
candidates without introducing much deadtime
• Best channels turned out to be auxilliary interferometer channels
• Example from inspiral analysis (similar for burst)
» Livingston 4km:
» Hanford 4km:
» Hanford 2km:
Net deadtime – 2.8%
Net deadtime – 0.3%
Net deadtime – 3.2%
• Must check that veto conditions would not veto a real
gravitational wave!
» Studied coupling using hardware injections in differential control & end
mass excitations
» Found some surprise couplings which may involve abandoning certain
vetoes
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Effectiveness of Vetoes
for S1 Playground Data
So, how do triggers & vetoes fit together in analysis pipeline?
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GW + Injections
Auxiliary Channels
Matched Filter
Filter
Template
Bank
Triggers
H1 clean
Not L1
-
Veto Triggers
L1 & H1
clean
L1 clean
Not H1
H1 Sees?
Yes
Dump
No
No
Coincidence?
Yes
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Event Candidates
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Sample Population Monte Carlo
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Binary Neutron star population
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Mass distribution derived from
population synthesis models
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Spatial distribution out to
200kpc including Milky Way,
LMC and SMC
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LMC and SMC contribute
about 12% of a Milky Way
equivalent Galaxy
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Signals injected into data
stream and used to determine
efficiency of pipeline to
detection of BNS population
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Testing with Hardware Injection
Inspiral Injections into hardware
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Testing with Hardware Injections
Pre-run: 2 x 1.4 Msun into L1:LSC-DARM_CTRL-EXC
T_inj
T0
SNR
D_eff
D_inj
%error
714029025.4249
714029025.4316
16.25
49.7
53.6
-7.85
714029115.4249
714029115.4314
30.91
26.1
26.7
-2.30
714029205.4249
14029205.4314
48.44
15.3
13.4
12.42
%error
Pre-run: 2 x 1.4 Msun into L1:LSC-ETMX-EXC
T_inj
T0
SNR
D_eff
D_inj
714029925.4249
714029925.4316
17.34
45.7
53.6
-17.29
71030015.42449
714030015.4316
35.63
22.3
26.7
-19.73
714030105.4249
714030105.4314
53.83
13.8
13.4
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LIGO First Science Run Synopsis
• Compact object inspiraling waveforms
» BNS coverage will include the Milky Way, plus LMC, SMC
» Black hole MACHO search under way
• Bursts/transient events
» 96 hours of 3X coincidence
» 2 different (complementary) filters applied to data
– frequency-time clustering algorithm, time-domain slope detector
» Efficiency using astrophysically motivated SNe waveforms and other.
• Continuous wave sources
» Initial searches target known EM sources, e.g.:
- PSR J1939+2134 (P= 1.557 ms, search and analysis in progress)
– Sco X-1 (in progress - 500 Hz - 600 Hz, multi-parameter search)
• Stochastic background
» Limiting sensitivity for W will be better than previous direct GW observational
determinations with resonant bars (narrowband)
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Plans for S2
• S2: 14 Feb – 14 April 2003
• Working groups
» have well defined primary analysis path for S2 data
» Plan to extend/enhance methodology from S1
» Some new tools are under development, e.g coherent multidetector analysis
• Veto development will be a major focus of the S2
detector characterization effort
» Desire to understand the instrumental origin of glitches
» Significant effort has been put into hardware injection plan
• Daily hardware injections of astrophysical signals to
help calibrate systematics
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Plans for S2
• Trigger generators to run in
real-time
» Burst searches: TFCLUSTERS,
POWER, SLOPE
» Inspiral searches
» Known pulsar demodulation
» External trigger searches
• Issues that caused problems
in S1 but have been fixed
» Accurate, real-time calibration
data available
» On-line monitoring tool to
provide alarms to control room
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Conclusion
• LIGO Scientific Operation
» Started in Aug. 2002!
» Analysis has been proceeding
» First results should be announced in Mar 2003
• Second run scheduled 14 Feb - 15 Apr 2003
» Sensitivity should be almost 10x better than S1
» Moving towards real-time analysis environment
• Looking forward to the TAMA/LIGO coincidence effort
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