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LIGO Data Analysis: Status and Plans

LIGO Data Analysis: Status and Plans. Patrick Brady University of Wisconsin-Milwaukee LIGO Scientific Collaboration. Outline of talk. First LIGO science data run (S1) Summary of run Organization of LIGO data analysis efforts Status of each effort

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LIGO Data Analysis: Status and Plans

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  1. LIGO Data Analysis: Status and Plans Patrick Brady University of Wisconsin-Milwaukee LIGO Scientific Collaboration

  2. Outline of talk • First LIGO science data run (S1) • 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 LIGO Scientific Collaboration - TAMA Symposium

  3. 10-18 10-20 10-21 10-19 LIGO Run Schedule • Science runs are interspersed with engineering runs and commissioning activities strain noise per root Hz Jul Jul Oct Oct Jun Jun Sep Sep Feb Aug Dec Feb Aug Nov Nov Mar Apr Mar Apr May May Jan 2002 Jan 2003 E10,… S3 • E7 • E8 • S1 • E9 S2 Now LIGO Scientific Collaboration - TAMA Symposium

  4. 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 LIGO Scientific Collaboration - TAMA Symposium

  5. 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 • 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% Green bands with black borders indicate locked segments LIGO Scientific Collaboration - TAMA Symposium

  6. 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 LIGO Scientific Collaboration - TAMA Symposium

  7. Burst Group Activities • Search for bursts of unknown origin/waveform • 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 LIGO Scientific Collaboration - TAMA Symposium

  8. 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 • 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 LIGO Scientific Collaboration - TAMA Symposium

  9. 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 LIGO Scientific Collaboration - TAMA Symposium

  10. Stochastic Group Activities • Analytic calculation of expected upper limits (~100 hrs): • W for LHO 2k-LHO 4k will provide the most stringent direct observationalupper 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 LIGO Scientific Collaboration - TAMA Symposium

  11. Playground Data Set • Representative sample of data distributed over run • 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 LIGO Scientific Collaboration - TAMA Symposium

  12. 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 • Different for TFCLUSTER, SLOPE, POWER Trigger in 200-400Hz band with duration ~100 sec LIGO Scientific Collaboration - TAMA Symposium

  13. Inspiral Trigger Generation: Templates • Use template based matched filtering algorithm • Template waveforms for non-spinning 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 LIGO Scientific Collaboration - TAMA Symposium

  14. 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. LIGO Scientific Collaboration - TAMA Symposium

  15. 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 LIGO Scientific Collaboration - TAMA Symposium

  16. 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: Net deadtime – 2.8% • Hanford 4km: Net deadtime – 0.3% • Hanford 2km: 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 LIGO Scientific Collaboration - TAMA Symposium

  17. Effectiveness of Vetoesfor S1 Playground Data So, how do triggers & vetoes fit together in analysis pipeline? LIGO Scientific Collaboration - TAMA Symposium

  18. Template Bank GW + Injections Auxiliary Channels Matched Filter Filter Triggers Veto Triggers - H1 clean Not L1 L1 & H1 clean L1 clean Not H1 H1 Sees? Yes No No Coincidence? Dump Yes LIGO Scientific Collaboration - TAMA Symposium Event Candidates

  19. Sample Population Monte Carlo • Binary Neutron star population • Mass distribution derived from population synthesis models • Spatial distribution out to 200kpc including Milky Way, LMC and SMC • LMC and SMC contribute about 12% of a Milky Way equivalent Galaxy • Signals injected into data stream and used to determine efficiency of pipeline to detection of BNS population LIGO Scientific Collaboration - TAMA Symposium

  20. Testing with Hardware Injection Inspiral Injections into hardware LIGO Scientific Collaboration - TAMA Symposium

  21. Testing with Hardware Injections Pre-run: 2 x 1.4 Msun into L1:LSC-DARM_CTRL-EXC Pre-run: 2 x 1.4 Msun into L1:LSC-ETMX-EXC LIGO Scientific Collaboration - TAMA Symposium

  22. 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) LIGO Scientific Collaboration - TAMA Symposium

  23. 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 multi-detector 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 LIGO Scientific Collaboration - TAMA Symposium

  24. 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 LIGO Scientific Collaboration - TAMA Symposium

  25. 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 LIGO Scientific Collaboration - TAMA Symposium

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