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

March 17, 2007 Baton Rouge, LABurst F2F Meeting I. Leonor2 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 correlated signal in two IFOs  large crosscorr

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

March 17, 2007 Baton Rouge, LABurst F2F Meeting I. Leonor4 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 p local = 0.57

March 17, 2007 Baton Rouge, LABurst F2F Meeting I. Leonor5 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 ~ 0.3z ~ 1.3

March 17, 2007 Baton Rouge, LABurst F2F Meeting I. Leonor6 GRB positions

March 17, 2007 Baton Rouge, LABurst F2F Meeting I. Leonor7 Preliminary search results, 25-ms crosscorrelation  no data quality cuts used  search GRBs up to GRB  use V2 calibrations when available (i.e. up to April 2006), otherwise use V1 calibrations

March 17, 2007 Baton Rouge, LABurst F2F Meeting I. Leonor8 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

March 17, 2007 Baton Rouge, LABurst F2F Meeting I. Leonor9 Preliminary search results, 100-ms crosscorrelation  search GRBs up to GRB  will application of data quality cuts improve results?

March 17, 2007 Baton Rouge, LABurst F2F Meeting I. Leonor10 hrss sensitivity, sine-gaussian, 250 Hz, linear polarization  mean hrss 50 = 7.6E-22 Hz -1/2  peak hrss 50 = 6.3E-22 Hz -1/2  mean hrss 90 = 3.7E-21 Hz -1/2  peak hrss 90 = 2.8E-21 Hz -1/2 50% confidence 90% confidence

March 17, 2007 Baton Rouge, LABurst F2F Meeting I. Leonor11 hrss sensitivity, sine-gaussian, 250 Hz, circular polarization  mean hrss 50 = 7.2E-22 Hz -1/2  E = 0.2 M sun at 20 Mpc (merger model)  peak hrss 50 = 5.6E-22 Hz -1/2  mean hrss 90 = 8.9E-22 Hz -1/2  E = 0.3 M sun at 20 Mpc (merger model)  peak hrss 90 = 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).

March 17, 2007 Baton Rouge, LABurst F2F Meeting I. Leonor12 hrss upper limit vs. average antenna factor (LHO)