1. GW Data Analysis (from an experimentalist’s point of view)
Gabriela González
Louisiana State University
Gravitation: A Decennial Perspective
CGPG, Penn State, June 8, 2003

2. Data Analysis: what data?
3 PDs, 6 signals,
4 DOF
AS_Q, or GW signal
Distances are controlled by feedback loops: we need to know what was there before we reduced the signals to keep cavities resonant: “calibration”.

3. Data analysis starts with good data
Data analysis starts with good data... that is a lot more than a good spectrum!
LLO interferometer S1 S2
(Feb-Apr ’03)

4. Keeping interferometer locked S1 run: 17days (408 hrs)
Seismic Noise in the
band

5. Calibrated spectrum
Calibration lines

6. S1: Calibration stability

7. (Preliminary) Results from S1 Upper Limits on Burst Sources
Upper limit in strain compared to prior (cryogenic bar) results:
S1: h < 5 x this result
IGEC 2000 : h < 1 x 10-17
Astone et al. 2001: h ~ 2 x 10-18
Upper limit in rate constrained by observation time:
S1: 17d, 3x coinc.- this result
IGEC - 90d (2X coinc.), 260d (3X coinc.)
Astone et al. - 90d
Excluded region,
90 % CL

8. (Preliminary) Results from S1 Upper Limits on Stochastic Background Sources
S1 (50 hrs, H2-L1): W0h2100 < 23
Current best upper limits:
Inferred: From Big Bang nucleosynthesis:
Measured: Garching-Glasgow interferometers:
Measured: EXPLORER-NAUTILUS:

9. (Preliminary) Results from S1 Upper Limits on Periodic Sources
S1: upper limits on J (1.284 Hz) amp < 10-22
Previous limits for same system:
40m: ~10-17
Glasgow detector: (2nd harm.)
At other frequencies, bars have set up limits near

10. (Preliminary) Results from S1 Upper Limits on NS Inspiral Sources
Mass distribution and effective distance
S1: 289 hrs, 2x: 116 hrs; R< 164/yr in Milky Way Equivalent Galaxy
(Expected: ~10-5/yr)
Previous searches:
LIGO 40m (’94, 25 hrs) /hr, 25 kpc
TAMA300 ’99 ( 6 hrs) /hr, ~ 1kpc
Glasgow-Garching ’89 (100 hrs) no events, ~1kpc
IGEC ’00-’01 (2yrs): no events, ~10 kpc

11. An eventful segment, with stable calibration
Loudest inspiral event (but LHO not locked  )

12. A “good” template match, a “bad” detector time

13. Statistics of the signal: gaussian, stationary?

14. Statistics of the signal: gaussian, stationary?

15. Conclusions Data analysis effort has started succesfully
Search methods are very diverse
Methods set upper limits, but are ready for detection
Data quality aspects are essential
Collaboration between theorists (sources), data analysis experts (methods) and experimentalists (data quality) is important.