1. The first AURIGA-TAMA joint analysis proposal BAGGIO Lucio ICRR, University of Tokyo A Memorandum of Understanding between the AURIGA experiment and the TAMA project has been signed in June 2005. A brief overview of the methods proposed for the startup of the joint analysis will be given. バッジョ ルー チョ アウリ ガ lbaggio@icrr.u-tokyo.ac.jp

2. IGEC-like burst event search and coincidence analysis

3. Gravitational wave burst events For fast (10ms) gw signals the impulse response of the optimal filter for the signal amplitude is an exponentially damped oscillation A candidate event in the gravitational wave channel is any single extreme value in a more or less constant time window. Background events come from the extreme distribution of the underlying stochastic process (in the ideal case Gaussian) This time window determines a dead time around large events Details of the analysis or duration of the template may change, but the general key concepts (time of arrival, amplitude, dead time) remains

4. Definition of arrival time/amplitude Fourier amplitude of burst gw arrival time peak amplitude of burst gw arrival time Templated search Templateless search sin-gaussian cos-gaussian dumped sinusoid … bandlimited, consistent amplitude and time estimate wide-band, unrelated time and amplitude estimates,

5. Timing error uncertainty (AURIGA, for  -like bursts )

6. The exchanged data time (hours) gaps minimum detectable amplitude (aka exchange threshold) events amplitude and time of arrival amplitude (Hz -1 ·10 -21 )

7. The exchange protocol The source of exchanged data are different data analysis applied to individual detector outputs. The partner experiments are only asked to follow a few general guidelines in order to characterize in a consistent way the parameters of the candidate events and the detector status at any time. Further data conditioning and background estimation are performed in a coordinated way

8. M-fold coincidence search A coincidence is defined when for all 0<i,j<M  t i – t j  <  t ij ~0.1 sec Coincidence windows  t ij depend on timing error, which is  non-gaussian at low SNR !  < 5% false dismissal for k =4.5 (Tchebyceff inequality)  strongly dependent on SNR ! The expected coincidence rate is given by: A reduction of the false alarm rate at the single detector implies a reduction in coincidence rate of the same amount.

9. Amplitude distributions of events The amplitude range is much wider than expected extreme distribution: non modeled outliers dominate at high SNR Cumulative power distribution of events TAMA Nov. 13-14, 2004 from the presentation at The 9th Gravitational Wave Data Analysis Workshop (December 15-18, 2004, Annecy, France) DT9 DT8 DT6 DT9 (before veto)

10. Amplitude distributions of events Amplitude distribution of events AURIGA Nov. 13-14, 2004 Remaining events after vetoing vetoed glitches epoch vetoes (50% of time) cumulative event rate above threshold false alarm rate [hour -1 ] after vetoing No more necessary since end of May 2005

11. False alarm reduction by amplitude selection Corollary: If the amplitude threshold is the same at every detector in the network, the selected events have naturally consistent amplitudes With a small increase of minimum amplitude, the false alarm rate drops dramatically.

12. Optimized data selection based on target amplitude and direction

13. Time variations of the sensitivity (and efficiency) H [Hz -1 ] 10 -21 – 2004, Nov 13-15 (weekend) Template: low efficiency intervals If time spans with low efficiency are vetoed, the global average efficiency remains almost unaffected, but the false alarms decrease. Given a precise template, it is possible to track the time vairiations of the the efficiency of detection for signals emitted at different amplitude target signal amplitude

14. Concept of directional sensitivity modulation     Assuming: amplitude H s =4 and declination=26 o Efficiency of joint (“AND”) detection for a point-like source and non-directional strategy periods which can be safely removed in a directional search measured amplitude

15. modulated signal amplitude time (hours) detected amplitude (Hz -1 ·10 -21 ) time (hours) Modulated signals or modulated sensitivity? original amplitude (Hz -1 ·10 -21 ) constant signal amplitude, modulated sensitivity

16. time (hours) Data selection at work (1) Duty time is shortened at each detector when efficiency is less than 50% A major false alarm reduction is achieved by excluding low amplitude events. amplitude (Hz -1 ·10 -21 )

17. Data selection at work (2) c   H s =4 H t =3 measured amplitude network efficiency

18. time (hours) Resampling statistics by time shifts amplitude (Hz -1 ·10 -21 ) We can approximately resample the stochastic process by time shift. In the resampled data the gw sources are off, along with any correlated noise. Ergodicity holds at least up to timescales of the order of one hour. The samples are independent as long as the shift is longer than the maximum time window for coincidence search (~ 1 second)

19. Efficiency and background dependency on threshold signal amplitude H s =4 declination=26 o

20. Efficiency and background dependency on threshold signal amplitude H s =4 declination=26 o H t =2.5 H t =3.0 H t =3.5 increasing minimum detectable amplitude A min =1 A min =1.3 A min =1.5 H t =4.0

21. Sky coverage H t =2.5 H t =3.0 H t =3.5

22. Improved exclusion regions for anisotropic sources 95% coverage exclusion region comparison for a point-like source (assuming 100 accidental coincidences are found above the minimum detectable amplitude). Different curves correspond to different thresholds directional search non-directional search

23. AURIGA-TAMA joint analysis

24. Joint AURIGA-TAMA working group activity 1 st STEP First data exchange fully conforming with the protocol; agreement on templates and coordinated software injections (LIGO MDC); preliminary implementation of the network software; presentation of status report at GWDAW2005 2 nd STEP Full implementation of analysis and official release of the network code and documentation. Final paper to be submitted to a regular journal. STEP-ZERO Outline of the most interesting analysis to be performed based on preliminary study of sensitivity and efficiency of the detectors; detailed specifications of the method (self- adapting directional coincidence search between candidate event lists from each detector) A working group for the joint burst search in LIGO and AURIGA has been formed, with the purpose to develop methodologies for bar/interferometer searches, to be tested on real data

25. AURIGA summer 2005 (low frequency suspensions installed) 21/05/2005

26. Noise power spectral density