Update on S5 Search for GRB and Gravitational Wave Burst Coincidence

1. Update on S5 Search for GRB and Gravitational Wave Burst Coincidence Isabel Leonor University of Oregon

2. correlated signal in two IFOs  large crosscorr Outline of GRB-GWB search • search for short-duration gravitational-wave bursts (GWBs) coincident with gamma-ray bursts (GRBs) • use GRB triggers observed by satellite experiments • Swift, HETE-2, INTEGRAL, IPN, Konus-Wind • include both “short” and “long” GRBs • search 180 seconds of LIGO data surrounding each GRB trigger (on-source segment) • waveforms of GWB signals associated with GRBs are not known • use crosscorrelation of two interferometers (IFOs) to search for associated GW signal • use crosscorrelation lengths of 25 ms and 100 ms to target short-duration GW bursts of durations ~1 ms to ~100 ms • use bandwidth of 40 Hz to 2000 Hz Burst F2F Meeting I. Leonor

3. sample GRB lightcurve (Swift) use 180-second LIGO on-source data surrounding GRB trigger LIGO IFO 1 crosscorrelate output of two IFOs look for largest crosscorrelation within 180-second on-source segment LIGO IFO 2 counts/sec trigger time 180 seconds on-source segments

4. Estimating probability of measured on-source largest crosscorr: Sample off-source distribution using 25-ms cc length • apply search to off-source segments to obtain crosscorrelation distribution • use time shifts to get enough statistics • largest crosscorrelation found in on-source search indicated by black arrow • probability is estimated using this distribution • off-source crosscorrelation distribution is determined for each IFO pair for each GRB trigger plocal = 0.57 Burst F2F Meeting I. Leonor

5. The GRB Sample for the S5 Run, as of March 3, 2007 • 153 GRBs as of March 3, 2007 • ~70% with double-IFO coincidence • ~40% with triple-IFO coincidence • ~25% with redshift • ~10% short-duration GRBs z ~ 0.3 z ~ 1.3 Burst F2F Meeting I. Leonor

6. GRB positions Burst F2F Meeting I. Leonor

7. Preliminary search results, 25-ms crosscorrelation • no data quality cuts used • search GRBs up to GRB 070227 • use V2 calibrations when available (i.e. up to April 2006), otherwise use V1 calibrations Burst F2F Meeting I. Leonor

8. Do excess events come from a particular time epoch? • test: remove events from September and October 2006 • removing some other pair of consecutive months doesn’t result in same reduction in significance • further study needed Burst F2F Meeting I. Leonor

9. Preliminary search results, 100-ms crosscorrelation • search GRBs up to GRB 070227 • will application of data quality cuts improve results? Burst F2F Meeting I. Leonor

10. hrss sensitivity, sine-gaussian, 250 Hz, linear polarization • mean hrss50 = 7.6E-22 Hz-1/2 • peak hrss50 = 6.3E-22 Hz-1/2 • mean hrss90 = 3.7E-21 Hz-1/2 • peak hrss90 = 2.8E-21 Hz-1/2 50% confidence 90% confidence Burst F2F Meeting I. Leonor

11. hrss sensitivity, sine-gaussian, 250 Hz, circular polarization • mean hrss50 = 7.2E-22 Hz-1/2 E = 0.2 Msun at 20 Mpc (merger model) • peak hrss50 = 5.6E-22 Hz-1/2 • mean hrss90 = 8.9E-22 Hz-1/2  E = 0.3 Msun at 20 Mpc (merger model) • peak hrss90 = 7.1E-22 Hz-1/2 50% confidence 90% confidence Due to modifications to the code, all GRBs, even those at bad positions, have determinable LHO-LLO upper limits (so far). Burst F2F Meeting I. Leonor

12. hrss upper limit vs. average antenna factor (LHO) Burst F2F Meeting I. Leonor