LIGO Laboratory 1 LIGO-G020530-00-E The Laser Interferometer Gravitational Wave Observatory LIGO at the threshold of science operations Albert Lazzarini LIGO Laboratory Carnegie Centennial Symposium on Astrophysics 21 November 2002 Pasadena, California
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LIGO-G020530-00-E LIGO Laboratory 1 The Laser Interferometer Gravitational Wave Observatory LIGO at the threshold of science operations Albert Lazzarini.
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LIGO Laboratory 1LIGO-G020530-00-E
The Laser Interferometer Gravitational Wave Observatory
……just a few of the just a few of the many individuals that many individuals that have contributed to have contributed to LIGOLIGO
Caltech
Livingston, LAHanford, WA
MIT
LIGO Laboratory 3LIGO-G020530-00-E
LIGO Scientific Collaboration
LIGO I Development Group: 21 Institutions, 26 Groups, 281 Membershttp://www.ligo.caltech.edu/LIGO_web/lsc/lsc.html
US Universities: Caltech• Carleton• Cornell• Cal State University Dominguez Hills• Florida• Louisiana State• Louisiana Tech• Michigan MIT• Oregon• Penn State• Southern• Syracuse• Texas-Brownsville• Wisconsin-Milwaukee
International Members:• ACIGA (Australia)• GEO 600 (UK/Germany)
• IUCAA (Pune, India)
US Agencies & Institutions • FNAL (DOE)• Goddard-GGWAG (NASA)• Harvard-Smithsonian
International partners (have MOUs with LIGO Laboratory):
• TAMA (Japan)• Virgo (France/Italy)
LIGO Laboratory 4LIGO-G020530-00-E
The LIGO Laboratory Sites
Hanford Observatory
Livingston ObservatoryCaltech
MIT
LIGO Laboratory 5LIGO-G020530-00-E
LIGO ObservatoriesLIGO Observatories
•
Hanford ObservatoryWashingtonTwo interferometers(4 km and 2 km arms)
• A gravitational wave causes the interferometers arm lengths to vary by stretching one arm while compressing the other, in the plane perpendicular to direction of travel.
• Searches for (long) periodic signals» Fourier transforms over Doppler shifted time
intervals.
• Search for stochastic GW background» Optimally weighted cross-correlated data from
different detectors.
• Detector characterization» Provide understanding of instrumental couplings to
GW channel.» Provide calibration for data analysis
Non-hierarchical Search
LIGO’s computational needsdominated by binary inspiral …100 GFLOPS @ 1 Solar Mass
LIGO Laboratory 15LIGO-G020530-00-E
Generic statements about the sensitivity of searches to poorly-modeled sources can straightforwardly be made from the t-f “morphology”…• longish-duration, small bandwidth (ringdowns, Sine-gaussians)• longish-duration, large bandwidth (chirps, Gaussians)• short duration, large bandwidth (merger)• In-between (Zwerger-Muller or Dimmelmeier SN waveforms)
•These SN waveforms are distance-calibrated; all others are parameterized by a peak or rms strain amplitude
ZM SN burst
chirp
merger
ringdown
ZM SN burstsBandwidth vs duration
Time frequency characterization of signals
- Exploiting a broadband detector -
LIGO Laboratory 16LIGO-G020530-00-E
Time Line
Now2002200019991Q 2Q 2Q1Q4Q3Q4Q 3Q
E1 E2 E5E3 E4
First Science
Data
Washington Earthquake
First Lock
InaugurationOne Arm
Power Recycled Michelson
Recombined Interferometer
Full Interferometer
E6
Washington 2KLouisiana 4kWashington 4K
4Q 2Q1Q 3Q
E7 E8
LHO 2k wire accident
10-17 10-18 10-19 10-20LLO strain noise at 150 Hz
2001
LIGO Laboratory 17LIGO-G020530-00-E
Sensitivity has steadily improved Sensitivity has steadily improved throughout commissioningthroughout commissioning
LIGO Laboratory 18LIGO-G020530-00-E
LIGO Sensitivity at Start of S1LIGO Sensitivity at Start of S1
LIGOS1 Run-----------“First
Upper Limit Run”
Aug – Sept 02
LIGO Laboratory 19LIGO-G020530-00-E
S1
G020482-00-D5
angular control
mirror actuationlow power operation
LIGO Laboratory 20LIGO-G020530-00-E
In-Lock Data Summary from S1In-Lock Data Summary from S1Red lines: integrated up time Green bands (w/ black borders): epochs of lock
» First pass analysis used ~2.5% of full data set to optimize
thresholds, refine algorithms, techniques
» Collaboration is now analyzing full S1 data set
– Not yet ready to give astrophysical results.
– Pre-prints should be available by February 2003
– First papers to be submitted by the end of March 2003
LIGO-G020530-00-E
Astrophysical Search Pipeline- example: burst group analysis -
LLO
LHO
IFO-IFOCoincidence
AndClustering
Sanity Checks
QuantifyUpper Limit
Quantifyefficiency
Simulated dataBased on Astrophysical
Source Knowledge
GW/VetoanticoincidenceEvent AnalysisTools
Glitch AnalysisAlgorithms (DMT)Feature Extraction
DB (T, T, SNR)
Aux Data (non GW)
…Aux Data (non GW)
StrainData
QualityCheck
Data split
Burst AnalysisAlgorithms (DSO)Feature Extraction
LDAS, DB (T, T, SNR)
GW/VetoanticoincidenceEvent AnalysisTools
Glitch AnalysisAlgorithms (DMT)Feature Extraction
DB (T, T, SNR)
Aux Data (non GW)
…Aux Data (non GW)
StrainData
QualityCheck
Data split
Burst AnalysisAlgorithms (DSO)Feature Extraction
LDAS, DB (T, T, SNR)
LIGO Laboratory 23LIGO-G020530-00-E
LIGO First Science Run Synopsis
• Quick-look based on ~2.5% sampling of data over 17 days plus Monte Carlo simulations injected into data subset is complete -- results under internal review
• Compact object inspiraling waveforms» Coverage includes the Galaxy, plus LMC, SMC
» Typical sensitivity for a binary neutron star population.
• Bursts/transient events» 96 hours of 3X coincidence» 2 different (complementary) filters applied to data
– frequency-time clustering algorithm (“tfclusters”)– time-domain slope detector (“slope”)– Calibration/efficiency using astrophysically motivated SNe waveforms, wavelets, etc.
• Continuous wave sources» Initial searches target known EM sources, e.g.:
- PSR J1939+2134 (P= 1.557 ms, search and analysis in progress)– Sco X-1 (in progress - 500 Hz - 600 Hz, multi-parameter search)
• Stochastic background» Limiting sensitivity for will be better than previous direct GW
observational determinations with resonant bars (narrowband)
LIGO Laboratory 24LIGO-G020530-00-E
Growing International Network of GW Growing International Network of GW InterferometersInterferometers
LIGO-LLO: 4km
LIGO-LHO: 2km, 4kmGEO: 0.6km VIRGO: 3km
TAMA: 0.3km
AIGO: (?)km
LIGO Laboratory 25LIGO-G020530-00-E
Event Localization With AnArray of GW Interferometers
SOURCE SOURCE
SOURCE SOURCE
LIGOLivingston
LIGOHanford
TAMA GEO
VIRGO
1 2
L =
t/c
cos = t / (c D12) ~ 0.5 deg
LIGO Laboratory 26LIGO-G020530-00-E
LIGO Run ScheduleLIGO Run Schedule
• Science runs are interspersed with engineering runs and commissioning to bring interferometer to design sensitivity
Jan 2002
Feb
Mar
Jun
May
Ap
r
Jul
Au
g
Oct
Sep
Nov
Jan 2003
Feb
Dec
Mar
Jun
May
Ap
r
Jul
Au
g
Oct
Sep
Nov
E7 E8 S2 S3S1
No
w
E9 E10,…
LIGO Laboratory 27LIGO-G020530-00-E
Targeted Noise Spectrum for S2
angular alignment controllers
digital-analog converters mirror actuators
shot noise (@ reduced power)
LIGO Laboratory 28LIGO-G020530-00-E
A Look to the FutureA Look to the Future
• Inherent facility limits» Gravity gradients (seismic waves)» Residual gas (vacuum)» Room to improve…