LIGO-G020530-00-E LIGO Laboratory 1 The Laser Interferometer Gravitational Wave Observatory LIGO at...

LIGO Laboratory 1LIGO-G020530-00-E

The Laser Interferometer Gravitational Wave Observatory

LIGO at the threshold of science operations

Albert LazzariniLIGO Laboratory

Carnegie Centennial Symposium on Astrophysics

21 November 2002Pasadena, California


Acknowledgements: LIGO LaboratoryAcknowledgements: LIGO Laboratory

……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 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)


The LIGO Laboratory Sites

Hanford Observatory

Livingston ObservatoryCaltech

MIT


LIGO ObservatoriesLIGO Observatories

•

Hanford ObservatoryWashingtonTwo interferometers(4 km and 2 km arms)

Livingston ObservatoryLouisianaOne interferometer (4km)


Interferometric GW DetectorsInterferometric GW Detectors

Principle of Detection:

• 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.

Time

LIGO-G020530-00-E

Interferometric GW DetectorsInterferometric GW Detectors


The Early Years:The Early Years:Caltech 40 Meter InterferometerCaltech 40 Meter Interferometer

•1/100th scale prototype for LIGO.

•Characterized fundamental noise sources.

•Instrumental as a technology proving ground.


New Window on UniverseNew Window on Universe

GRAVITATIONAL WAVES WILL GIVE A NEW AND UNIQUE VIEW OF THE DYNAMICS OF THE UNIVERSE.

EXPECT SOURCES: BLACK HOLES, SUPERNOVAE, PULSARS ANDCOMPACT BINARY SYSTEMS.

POSSIBILITY FOR THE UNEXPECTED IS VERY REAL!


Compact Binary SourcesCompact Binary Sources

V. Kalogera (population synthesis)


Burst SourcesBurst Sources

gravitational waves

Rate1/50 yr - our galaxy3/yr - Virgo cluster


Periodic SourcesPeriodic SourcesOn a 1TFLOPS computer it would take more than 10,000 yr to perform an

all-sky search over a 1000 Hz band for an observation time of 4 months.

* Graphs from Brady, Creighton, Cutler, and Schutz, gr-qc/9702050

Data must be corrected for each source position on the sky

=10

-5 @ 1

0 kp

c=

10-6 @

10

kpc


Stochastic Background SourcesStochastic Background Sources

Analog from electromagnetic spectrum

Upper limit possiblewith initial LIGO interferometers:GW ~10-5

E7 Run


LIGO Data AnalysisLIGO Data Analysis

• Different scientific topics - different analysis methods

• Searches for (short) transient signals» Inspiral: optimal filtering.» Bursts: time-frequency methods.

• 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


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 -


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


Sensitivity has steadily improved Sensitivity has steadily improved throughout commissioningthroughout commissioning


LIGO Sensitivity at Start of S1LIGO Sensitivity at Start of S1

LIGOS1 Run-----------“First

Upper Limit Run”

Aug – Sept 02


S1

G020482-00-D5

angular control

mirror actuationlow power operation


In-Lock Data Summary from S1In-Lock Data Summary from S1Red lines: integrated up time Green bands (w/ black borders): epochs of lock

•August 23 – September 9, 2002: 408 hrs (17 days).•H1 (4km): duty cycle 57.6% ; Total Locked time: 235 hrs •H2 (2km): duty cycle 73.1% ; Total Locked time: 298 hrs •L1 (4km): duty cycle 41.7% ; Total Locked time: 170 hrs

•Double coincidences: •L1 && H1 : duty cycle 28.4%; Total coincident time: 116 hrs •L1 && H2 : duty cycle 32.1%; Total coincident time: 131 hrs •H1 && H2 : duty cycle 46.1%; Total coincident time: 188 hrs

•Triple Coincidence: L1, H1, and H2 : duty cycle 23.4% ;•Total coincident time: 95.7 hrs

H1: 235 hrs H2: 298 hrs L1: 170 hrs 3X: 95.7 hrs


LIGO First Science Run Synopsis

• LIGO is now more sensitive than any prior

broadband instrument

• Analysis is in progress

» 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 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)


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


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 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,…


Targeted Noise Spectrum for S2

angular alignment controllers

digital-analog converters mirror actuators

shot noise (@ reduced power)


A Look to the FutureA Look to the Future

• Inherent facility limits» Gravity gradients (seismic waves)» Residual gas (vacuum)» Room to improve…

• Advanced LIGO» R&D underway…» Seismic noise 4010 Hz» Thermal noise 1/15th » Shot noise 1/10th


Advanced LIGO:Advanced LIGO:Cubic Law for “Cubic Law for “WindowWindow” on the Universe” on the Universe

Initial LIGO

Advanced LIGO

Improve amplitude sensitivity by a factor of 10x…

…number of sources goes up 1000x!

Virgo cluster


LIGO Science Has Started

• LIGO has started taking data

• LIGO had a its first science run this summer» Collaboration is currently carrying out the data analysis

– CW sources– Compact binary coalescences– Bursts– Stochastic background

» First results should be announced in Feb-Mar 2003

• Second run scheduled 14 Feb - 15 Apr 2003» Sensitivity should be almost 10x better than S1

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