LIGO Update ------------ “ The Search for Gravitational Waves”

1. LIGO Update------------ “The Search for Gravitational Waves” Barry Barish Caltech Trustees 10-Sept-02

2. Laser Interferometer Gravitational-wave Observatory • Goals • First direct detection of gravitational waves • Open new window on the universe – “gravitational wave astronomy” • NSF funded construction in 1994 for $296M • Caltech has fiduciary responsibility • Joint Caltech/MIT technical and scientific team • Construction completed in both Louisiana and Washington in 2000 • Commissioning, Operations and Scientific Programs • First Interferometer “locked” – (Oct 2000) • First coincidence running of both sites – (Dec 2001) • First scientific data run “upper limits” – (Sept 2002) • Search for gravitational waves – (2003 through 2006) • We propose to install “Advanced LIGO” in 2007 • Cost ~ $125M total -- international collaboration Caltech Board of Trustees

3. University of Adelaide ACIGA Australian National University ACIGA California State Dominquez Hills Caltech LIGO Caltech Experimental Gravitation CEGG Caltech Theory CART University of Cardiff GEO Carleton College Cornell University University of Florida @ Gainesville Glasgow University GEO University of Hannover GEO Harvard-Smithsonian India-IUCAA IAP Nizhny Novgorod Iowa State University Joint Institute of Laboratory Astrophysics LIGO Livingston LIGOLA LIGO Hanford LIGOWA Louisiana State University Louisiana Tech University MIT LIGO Max Planck (Garching) GEO Max Planck (Potsdam) GEO University of Michigan Moscow State University NAOJ - TAMA University of Oregon Pennsylvania State University Exp Pennsylvania State University Theory Southern University Stanford University University of Texas@Brownsville University of Western Australia ACIGA University of Wisconsin@Milwaukee LIGO Scientific CollaborationMember Institutions LSC Membership 35 institutions > 350 collaborators International India, Russia, Germany, U.K, Japan and Australia. The international partners are involved in all aspects of the LIGO research program. Caltech Board of Trustees

4. Livingston Optical Telescopebroad outreach/education program Draft building concept utilizes surplus beam tube enclosures on raised footings with roll-off roof Proposed telescope location on fire access road gives clear view to south Telescope facts: 16 inch Richey Chretien telescope built by Optical Guidance Systems Telescope provided by state funds via LSU. LIGO provides site and internet connection and incorporates telescope use into outreach program. Internet accessible to facilitate classroom use Caltech Board of Trustees

5. BudgetLIGO Operations (2002 thru 2006) • Operations of LIGO funded beginning in 2002 for 5 years at a total funding of $160M • We function as one distributed laboratory (LIGO Laboratory) • Caltech (85 staff); MIT (25staff); Hanford (25 staff); Livingston (25 staff) • Advanced LIGO construction (not included) to be proposed next year + $5M Caltech Board of Trustees

6. LIGO at Caltech • Faculty • Barish, Drever, Libbrecht, Prince and Weinstein (Exp) & Thorne(Th) • Scientists/Postdocs/Students • PhD theses; talented junior and senior scientists • LIGO Management • Directorate, Administration • LIGO Technical • Engineering center – precision engineering; controls; electronics • 40 meter prototype; Optical laboratories, etc • LIGO Data Analysis and Computing • Simulations; Analysis infrastructure, Networking, Data Archive • Scientific data analysis efforts • Source Simulations – Numerical Relativity Caltech Board of Trustees

7. Einstein’s Theory of Gravitation gravitational waves Newton’s Theory “instantaneous action at a distance” Einstein’s Theory information carried by gravitational radiation at the speed of light • A necessary consequence of Special Relativity with its finite speed for information transfer • Time dependent gravitational fields come from the acceleration of masses and propagate away from their sources as a space-time warpage at the speed of light Caltech Board of Trustees

8. Direct Detectionastrophysical sources Gravitational Wave Astrophysical Source Terrestrial detectors LIGO, TAMA, Virgo,AIGO Detectors in space LISA Caltech Board of Trustees

9. Interferometers terrestrial free masses free masses International network (LIGO, Virgo, GEO, TAMA, AIGO) of suspended mass Michelson-type interferometers on earth’s surface detect distant astrophysical sources suspended test masses Caltech Board of Trustees

10. Suspended Mass Interferometerthe concept As a wave passes, the arm lengths change in different ways…. • Arms in LIGO are 4km • Current technology then allows one to measure h = dL/L ~ 10-21which turns out to be an interesting target • An interferometric gravitational wave detector • A laser is used to measure the relative lengths of two orthogonal cavities (or arms) …causing the interference pattern to change at the photodiode Caltech Board of Trustees

11. How Small is 10-18 Meter? One meter, about 40 inches Human hair, about 100 microns Wavelength of light, about 1 micron Atomic diameter, 10-10 meter Nuclear diameter, 10-15 meter LIGO sensitivity, 10-18 meter Caltech Board of Trustees

12. What Limits Sensitivityof Interferometers? • 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 Board of Trustees

13. Noise Floor40 m prototype sensitivity demonstration • displacement sensitivity • in 40 m prototype. • comparison to predicted contributions from various noise sources Caltech Board of Trustees

14. LIGOlong baseline interferometers (4 km) Laser Interferometer Gravitational-wave Observatory (LIGO) Hanford Observatory Livingston Observatory Caltech Board of Trustees

15. LIGO Livingston Observatory Caltech Board of Trustees

16. LIGO Hanford Observatory Caltech Board of Trustees

17. 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 Board of Trustees

18. LIGOvacuum equipment Caltech Board of Trustees

19. LIGO requirements Surface uniformity < 1 nm rms Scatter < 50 ppm Absorption < 2 ppm ROC matched < 3% Internal mode Q’s > 2 x 106 Core Opticsfused silica • LIGO measurements • central 80 mm of 4ITM06 (Hanford 4K) • rms  = 0.16 nm • optic far exceeds specification. Surface figure = / 6000 Caltech Board of Trustees

20. Core Optics installation and alignment Caltech Board of Trustees

21. Interferometerlocking end test mass Requires test masses to be held in position to 10-10-10-13 meter: “Locking the interferometer” Light bounces back and forth along arms about 150 times Light is “recycled” about 50 times input test mass Laser signal Caltech Board of Trustees

22. Lock Acquisition Caltech Board of Trustees

23. Composite Video LIGO watching the interferometer lock Y Arm Laser X Arm signal Caltech Board of Trustees

24. 2 min LIGO watching the interferometer lock Y arm X arm Y Arm Reflected light Anti-symmetricport Laser X Arm signal Caltech Board of Trustees

25. Engineering Run detecting earthquakes From electronic logbook 2-Jan-02 An earthquake occurred, starting at UTC 17:38. The plot shows the band limited rms output in counts over the 0.1- 0.3Hz band for four seismometer channels. We turned off lock acquisition and are waiting for the ground motion to calm down. Caltech Board of Trustees

26. 17:03:03 01/02/2002 ========================================================================= Seismo-Watch Earthquake Alert Bulletin No. 02-64441 ========================================================================= Preliminary data indicates a significant earthquake has occurred: Regional Location: VANUATU ISLANDS Magnitude: 7.3M Greenwich Mean Date: 2002/01/02 Greenwich Mean Time: 17:22:50 Latitude: 17.78S Longitude: 167.83E Focal depth: 33.0km Analysis Quality: A Source: National Earthquake Information Center (USGS-NEIC) Seismo-Watch, Your Source for Earthquake News and Information. Visit http://www.seismo-watch.com ========================================================================= All data are preliminary and subject to change. Analysis Quality: A (good), B (fair), C (poor), D (bad) Magnitude: Ml (local or Richter magnitude), Lg (mblg), Md (duration), ========================================================================= Caltech Board of Trustees

27. Detecting the Earth Tides Sun and Moon Caltech Board of Trustees

28. Caltech Board of Trustees

29. LIGO Goals and Priorities • Interferometer performance • Integrate commissioning and data taking consistent with obtaining one year of integrated data at h = 10-21 by end of 2006 • Physics results from LIGO I • Initial upper limit results by early 2003 • First search results in 2004 • Reach LIGO I goals by 2007 • Advanced LIGO • Prepare advanced LIGO proposal this fall • International collaboration and broad LSC participation • Advanced LIGO installation beginning by 2007 Caltech Board of Trustees

30. Preliminary Caltech Board of Trustees

31. Caltech Board of Trustees

32. Astrophysical Sources the search for gravitational waves • 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 Board of Trustees

33. “Stochastic Background” cosmological signals ‘Murmurs’ from the Big Bang signals from the early universe Cosmic microwave background Caltech Board of Trustees

34. Stochastic Backgroundcoherence plot LHO 2K & LLO 4K Caltech Board of Trustees

35. Stochastic Background projected sensitivities Caltech Board of Trustees

36. Advanced LIGO Multiple Suspension Active Seismic Saphire Optics Higher Power Laser Caltech Board of Trustees

37. Advanced LIGO • Enhanced Systems • improved laser • suspension • seismic isolation • test mass material • narrow band optics Improvement factor ~ 104 Caltech Board of Trustees

38. Gravitational-wave Astronomyfrequency range Audio band • EM waves are studied over ~20 orders of magnitude • (ULF radio -> HE -rays) • Gravitational Waves over ~10 orders of magnitude • (terrestrial + space) LIGO I (2003-06) Adv LIGO (2008 -) LISA 2011- Caltech Board of Trustees