Probing the Universe for Gravitational Waves LIGO Barry Barish Caltech 5-June-03

1. Probing the Universe for Gravitational WavesLIGOBarry BarishCaltech5-June-03 LIGO / Caltech LIGO-G030284-00-M

2. Gravitational Wavessources and detection Gravitational Wave Astrophysical Source Terrestrial detectors LIGO, TAMA, Virgo,AIGO Detectors in space LISA Caltech Colloquium

3. Detecting a passing wave …. Free masses Caltech Colloquium

4. Detecting a passing wave …. Interferometer Caltech Colloquium

5. As a wave passes, the arm lengths change in different ways…. Interferometer Concept • Arms in LIGO are 4km • Measure difference in length to one part in 1021 or 10-18 meters • Laser used to measure relative lengths of two orthogonal arms …causing the interference pattern to change at the photodiode Caltech Colloquium

6. The Laboratory Sites Laser Interferometer Gravitational-wave Observatory (LIGO) Hanford Observatory Livingston Observatory Caltech Colloquium

7. LIGO: A View from the Bulldozers Caltech Colloquium

8. From Bulldozers to First Results Caltech Colloquium

9. Construction in Washington Caltech Colloquium

10. Flooding in Louisiana Caltech Colloquium

11. LIGO Facilitiesbeam tube enclosure • minimal enclosure • reinforced concrete • no services

12. LIGO I the noise floor • Interferometry is limited by three fundamental noise sources • seismic noise at the lowest frequencies • thermal noise at intermediate frequencies • shot noise at high frequencies • Many other noise sources lurk underneath and must be controlled as the instrument is improved Caltech Colloquium

13. Dirt Moving to Mechanical arches and beam tubes Concrete Arches beamtube transport girth welding beamtube install Caltech Colloquium

14. LIGObeam tube • LIGO beam tube under construction in January 1998 • 65 ft spiral welded sections • girth welded in portable clean room in the field 1.2 m diameter - 3mm stainless 50 km of weld NO LEAKS !! Caltech Colloquium

15. LIGO I the noise floor • Interferometry is limited by three fundamental noise sources • seismic noise at the lowest frequencies • thermal noise at intermediate frequencies • shot noise at high frequencies • Many other noise sources lurk underneath and must be controlled as the instrument is improved Caltech Colloquium

16. Beam Tube bakeout • I = 2000 amps for ~ 1 week • no leaks !! • final vacuum at level where not limiting noise, even for future detectors Caltech Colloquium

17. LIGO I the noise floor • Interferometry is limited by three fundamental noise sources • seismic noise at the lowest frequencies • thermal noise at intermediate frequencies • shot noise at high frequencies • Many other noise sources lurk underneath and must be controlled as the instrument is improved Caltech Colloquium

18. Vacuum Chambersvibration isolation systems • Reduce in-band seismic motion by 4 - 6 orders of magnitude • Compensate for microseism at 0.15 Hz by a factor of ten • Compensate (partially) for Earth tides Caltech Colloquium

19. damped springcross section Seismic Isolationsprings and masses Caltech Colloquium

20. 102 100 10-2 10-6 Horizontal 10-4 10-6 10-8 Vertical 10-10 Seismic Isolationperformance HAM stack in air BSC stackin vacuum Caltech Colloquium

21. LIGOvacuum equipment Caltech Colloquium

22. LIGO Livingston Observatory Caltech Colloquium

23. Welcome to Louisiana pet alligator collecting bullet holes Caltech Colloquium

24. LIGO Hanford Observatory Caltech Colloquium

25. Gliches at Hanford a view from the bridge LIGO as a car stop desert on fire LIGO as a fire break Caltech Colloquium

26. Seismic Isolationsuspension system suspension assembly for a core optic • support structure is welded tubular stainless steel • suspension wire is 0.31 mm diameter steel music wire • fundamental violin mode frequency of 340 Hz Caltech Colloquium

27. LIGO Optic Substrates: SiO2 25 cm Diameter, 10 cm thick Homogeneity < 5 x 10-7 Internal mode Q’s > 2 x 106 Polishing Surface uniformity < 1 nm rms Radii of curvature matched < 3% Coating Scatter < 50 ppm Absorption < 2 ppm Uniformity <10-3 Caltech Colloquium

28. Core Optics installation and alignment Caltech Colloquium

29. LIGO Construction Complete Caltech Colloquium

30. LIGO Inauguration Whitcomb Sanders Lazzarini Caltech Boss The masses NSF Boss Caltech Colloquium

31. Locking the Interferometers Caltech Colloquium

32. Composite Video LIGO “first lock” Y Arm Laser X Arm signal Caltech Colloquium

33. 2 min Watching the Interferometer Lock Y arm X arm Y Arm Reflected light Anti-symmetricport Laser X Arm signal Caltech Colloquium

34. Lock Acquisition Matt Evans Caltech grad student Caltech Colloquium

35. Detecting Earthquakes From electronic logbook 2-Jan-02 An earthquake occurred, starting at UTC 17:38. Caltech Colloquium

36. Detecting the Earth TidesSun and Moon Eric Morgenson Caltech Sophomore Summer ‘99 Caltech Colloquium

37. Making LIGO Work Caltech Colloquium

38. Tidal Compensation Data Tidal evaluation on 21-hour locked section of S1 data Predicted tides Feedforward Feedback Residual signal on voice coils Residual signal on laser Caltech Colloquium

39. Controlling angular degrees of freedom Caltech Colloquium

40. LIGO Control Room Caltech Colloquium

41. DESIGN CONSTRUCTION OPERATION SCIENCE Detector R&D LIGO Laboratory MIT + Caltech ~140 people Director: Barry Barish LIGO Science Collaboration 44 member institutions > 400 scientists Spokesperson: Rai Weiss UK Germany Japan Russia India Spain Australia $ National Science Foundation LIGO Caltech Colloquium

42. Worldwide Network simultaneously detect signal LIGO Virgo GEO TAMA AIGO decompose the polarization of gravitational waves detection confidence locate the sources Caltech Colloquium

43. Improving the Sensitivity • Seismic noise & vibration limit at low frequencies • Atomic vibrations (Thermal Noise) inside components limit at mid frequencies • Quantum nature of light (Shot Noise) limits at high frequencies • Myriad details of the lasers, electronics, etc., can make problems above these levels Caltech Colloquium

44. LIGO Sensitivity Livingston 4km Interferometer May 01 First Science Run 17 days - Sept 02 Jan 03 Second Science Run 59 days - April 03 Caltech Colloquium

45. The First Science Run s1 Caltech Colloquium

46. Sensitivity during S1 • LIGO S1 Run • ---------- • “First • Upper Limit • Run” • 23 Aug–9 Sept 2002 • 17 days • All interferometers in power recycling configuration LHO 2Km LHO 4Km LLO 4Km GEO in S1 RUN ---------- Ran simultaneously In power recycling Lesser sensitivity Caltech Colloquium

47. Astrophysical Sourcessignatures • Compact binary inspiral: “chirps” • NS-NS waveforms are well described • BH-BH need better waveforms • search technique: matched templates • Supernovae / GRBs: “bursts” • burst signals in coincidence with signals in electromagnetic radiation • prompt alarm (~ one hour) with neutrino detectors • Pulsars in our galaxy: “periodic” • search for observed neutron stars (frequency, doppler shift) • all sky search (computing challenge) • r-modes • Cosmological Signals “stochastic background” Caltech Colloquium

48. In-Lock Data Summary from S1 H1: 235 hrs H2: 298 hrs L1: 170 hrs 3X: 95.7 hrs Red lines: integrated up timeGreen 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 95.7 hours Caltech Colloquium

49. Compact binary collisions“chirps” • Neutron Star – Neutron Star • waveforms are well described • Black Hole – Black Hole • need better waveforms • Search: matched templates Caltech Colloquium

50. Searching Technique binary inspiral events • Use template based matched filtering algorithm • Template waveforms for non-spinning binaries • 2.0 post-Newtonian approx. • D: effective distance; a: phase • Discrete set of templates labeled by I=(m1, m2) • 1.0 Msun < m1, m2 < 3.0 Msun • 2110 templates • At most 3% loss in SNR s(t) = (1Mpc/D) x [ sin(a) hIs (t-t0) + cos(a) hIc (t-t0)] Caltech Colloquium