LIGO-G Z External Triggers Circulation only within LIGO I authorship list Status of the Triggered Burst Search (highlights from LIGO DCC# T Z, “Triggered search analysis of S1 data associated with X-ray Flash XRF020903”) R. Rahkola, R. Frey (U. Oregon) Sz. Márka (CIT) S. Mohanty, S. Mukherjee (AEI) LSC Meeting, LLO, March 17, 2003

LIGO-G Z External Triggers Circulation only within LIGO I authorship list LSC Meeting, March 17-20, S1 Analysis – Objectives S1 Objective: Obtain a confidence interval estimate for h rms on the GW signal associated with trigger(s) received from GCN Triggered Search (n) : A search for GWBs in conjunction with non-GW astronomical observations. † FMR: L.S. Finn, S.D. Mohanty, J. Romano, “Detecting an association between Gamma Ray and Gravitational Wave Bursts,” Phys. Rev. D v60, p (1999)L.S. Finn, S.D. Mohanty, J. Romano, “Detecting an association between Gamma Ray and Gravitational Wave Bursts,” Phys. Rev. D v60, p (1999) Approach: Combine the (weak?) GW signals from several trigger timestamps in order to improve the SNR. [Note: averages properties of GW signals over the GRB source population] Baseline goal: Implementation of the FMR algorithm † in the context of the three LIGO IFOs

LIGO-G Z External Triggers Circulation only within LIGO I authorship list LSC Meeting, March 17-20,  6 triggers received (vs. 13 triggers for E7)  Only 1 trigger coincident with LLO-LHO lock stretch (XRF020903)!! S1 Analysis – Triggers Received

LIGO-G Z External Triggers Circulation only within LIGO I authorship list LSC Meeting, March 17-20, S1 Analysis – Algorithm for a Confidence Interval Estimate Only 1 trigger  precludes direct application of FMR method (in toto). FMR methodIn practice  Assume stationary GW data  Calculate the cross- correlation (c.c.) statistic: Compare  A control population (“off-source”) with  A test population (“on-source”)  Data conditioning (calibration, removal of non-stationary resonances, bandpass filtering)   “off-source” data, { X off }  A test datapoint (“on-source”)  “on-source” datapoint, X on

LIGO-G Z External Triggers Circulation only within LIGO I authorship list LSC Meeting, March 17-20, † F-C: G. Feldman and R. Cousins, “Unified approach to the classical statistical analysis of small signals,” Phys. Rev. D, v57, p3873. S1 Analysis – Where do we break from FMR?  Characterize distribution of off-source c.c. statistics as Gaussian: mean μ off, standard deviation σ off  Normalize on-source c.c. statistic by μ off, σ off  Look up interval estimate from F-C †  Revert interval estimate to appropriate units (strain) not physically meaningful yet?!  Account for data conditioning effects (i.e. frequency region removal) to obtain interval estimate on h rms  A test datapoint (“on-source”)  “on-source” datapoint, X on

LIGO-G Z External Triggers Circulation only within LIGO I authorship list LSC Meeting, March 17-20, S1 Analysis – Tuning & Production Pipelines

LIGO-G Z External Triggers Circulation only within LIGO I authorship list LSC Meeting, March 17-20, S1 Analysis – Data Sets Validation Data Off-source Data On-source Data Playground Data XRF Trigger GPS L1 and H2 lock stretches courtesy of G. Gonzalez (LSU)

LIGO-G Z External Triggers Circulation only within LIGO I authorship list LSC Meeting, March 17-20, S1 Analysis – Interval Estimate for XRF % confidence level  Interval estimate (I.E.) for (from F-C, table X): [min,max) = [0, 2.05x ) ← upper limit!  Extrapolate to an upper limit on h rms † : h rms < 1.13x † for 0.465ms GWB with flat spectral density across Hz (& no power outside this band)

LIGO-G Z External Triggers Circulation only within LIGO I authorship list LSC Meeting, March 17-20, S1 Analysis – Issues Addressed  Translation of trigger information  Propagation time delay between IFOs  Start of GWB relative to XRF  LIGO internal DAQ time shift at XRF arrival time  Absolute IFO-crossing time of XRF  Data Conditioning  Possible introduction of artifacts into GW data  Account for strain lost in removed frequency regions  Differences in calibrations between IFOs  Differences in sensitive bands for IFOs  Presence of non-stationarity (before vs. after) oContribution of frequency resonances  Off-source population  Effect of data conditioning  Number of samples, time shift between samples  Possible errors in μ off, σ off  On-source data  Extrapolation of interval estimate to (physically-meaningful) upper limit on h rms

LIGO-G Z External Triggers Circulation only within LIGO I authorship list LSC Meeting, March 17-20, S2 Analysis – Comparison with S1  Calibrate, bandpass filter, & remove non- stationary frequency resonances from GW data  Construct off-source distribution of c.c. statistics  Extrapolate I.E. on to I.E. on h rms  Single trigger precludes FMR method being used completely  Multiple triggers(?) will allow FMR method to be used completely  Non-stationary resonances were identified using distributions of c.c. statistics  Non-stationary resonances are identified using independent methods  Used a single calibration function for both IFOs  Time-dependent calibrated data available  Analysis performed mainly in Matlab ®  Comparison of results obtained with LDAS and with Matlab ®  No estimation of systematic uncertainties  Include estimates of systematic uncertainties S1 AnalysisS2 Analysis

LIGO-G Z External Triggers Circulation only within LIGO I authorship list LSC Meeting, March 17-20,  21 triggers received (vs. 6 triggers for S1)  1 trigger with accurate direction information and coincident with LLO-LHO triple lock stretch (GRB030226) !! S2 Analysis – Triggers received during S2 (so far)

LIGO-G Z External Triggers Circulation only within LIGO I authorship list LSC Meeting, March 17-20, PRELIMINARY NUMBERS! S2 Analysis – Interval Estimate for GRB Triple coincidence – Breaks down as three cases:  H1 & L1 (95% confidence level): I.E. for : [0, 4.33x ), upper limit for h rms † : 1.50x  H2 & L1 :  H1 & H2 : † For 2.5-ms burst with flat spectral density ( Hz)

LIGO-G Z External Triggers Circulation only within LIGO I authorship list LSC Meeting, March 17-20, S2 Analysis – Future Work Needed  Multi-IFO coincident lock stretches  Single- vs. Multiple-trigger analysis  Using triggers with annulus directional information  Optimal treatment of long-term non-stationarity  Comparison/Combination of LDAS & Matlab ® implementations  Accounting for systematic uncertainties