GW Data AnalysisGW Data Analysis(from an experimentalist’s point of view)(from an experimentalist’s point of view)
Gabriela GonzálezLouisiana State University
Gravitation: A Decennial PerspectiveCGPG, Penn State, June 8, 2003
3 PDs, 6 signals, 4 DOF
Data Analysis: what data?Data Analysis: what data?
Distances are controlled by feedback loops: we need to know what was there before we reduced the signals to keep cavities resonant: “calibration”.
AS_Q, or GW signalAS_Q, or GW signal
Data analysis starts with good data... Data analysis starts with good data... that is a lot more than a good spectrum!that is a lot more than a good spectrum!
S1
LLO interferometer
S2(Feb-Apr ’03)
Keeping interferometer lockedKeeping interferometer lockedS1 run: 17days (408 hrs)S1 run: 17days (408 hrs)
Seismic Noise in the band
Calibrated spectrumCalibrated spectrum
Calibration lines
S1: Calibration stabilityS1: Calibration stability
(Preliminary) Results from S1(Preliminary) Results from S1Upper Limits on Burst SourcesUpper Limits on Burst Sources
Excluded region,90 % CL
• Upper limit in strain compared to prior (cryogenic bar) results:
S1: h < 5 x 10-17 - this resultIGEC 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 resultIGEC - 90d (2X coinc.), 260d (3X coinc.)Astone et al. - 90d
(Preliminary) Results from S1(Preliminary) Results from S1Upper Limits on Stochastic Upper Limits on Stochastic
Background SourcesBackground SourcesS1 (50 hrs, H2-L1): h2
< 23
Current best upper limits:
• Inferred: From Big Bang
nucleosynthesis:
• Measured: Garching-Glasgow
interferometers:
• Measured: EXPLORER-
NAUTILUS:
GW ( f ) d ln f 110 5
GW ( f ) 3105
GW (907Hz) 60
(Preliminary) Results from S1(Preliminary) Results from S1Upper Limits on Periodic Upper Limits on Periodic
SourcesSources
S1: upper limits on J1939+2134 (1.284 Hz)amp < 10-22
Previous limits for same system:• 40m: ~10-17
• Glasgow detector: 10-20 (2nd harm.)
At other frequencies, bars have set up limits near 10 -24
(Preliminary) Results from S1(Preliminary) Results from S1Upper Limits on NS Inspiral Upper Limits on NS Inspiral
SourcesSourcesMass 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) 0.5/hr, 25 kpc• TAMA300 ’99 ( 6 hrs) 0.6/hr, ~ 1kpc• Glasgow-Garching ’89 (100 hrs) no events, ~1kpc• IGEC ’00-’01 (2yrs): no events, ~10 kpc
An eventful segment, withAn eventful segment, withstable calibrationstable calibration
Loudest inspiral event (but LHO not locked )
A “good” template match,A “good” template match,a “bad” detector timea “bad” detector time
Statistics of the signal: Statistics of the signal: gaussian, stationary?gaussian, stationary?
Statistics of the signal: Statistics of the signal: gaussian, stationary?gaussian, stationary?
ConclusionsConclusions
• 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.
