1. LIGO-G050250-00-W The Status of Gravitational-Wave Detectors Reported on behalf of LIGO colleagues by Fred Raab, LIGO Hanford Observatory

2. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors2 Reach of Gravitational Wave Detectors is Rapidly Expanding Windows of opportunity GWs a known phenomenon, but undetected as yet Resonant-bar & laser detectors Worldwide networks of terrestrial detectors LIGO: the first generation of km-scale detectors Moving toward the future

3. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors3 Different Frequency Bands of Detectors and Sources l EM waves are studied over ~20 orders of magnitude »(ULF radio  HE  rays) l Gravitational Wave coverage over ~8 orders of magnitude » (terrestrial + space) Audio band spaceterrestrial

4. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors4 Catching Waves From Orbiting Black Holes and Neutron Stars Sketches courtesy of Kip Thorne

5. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors5 Gravitational Waves the evidence Neutron Binary System – Hulse & Taylor PSR 1913 + 16 -- Timing of pulsars   17 / sec Neutron Binary System separated by 10 6 miles m 1 = 1.4m  ; m 2 = 1.36m  ;  = 0.617 Prediction from general relativity spiral in by 3 mm/orbit rate of change orbital period ~ 8 hr Emission of gravitational waves

6. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors6 Basic Signature of Gravitational Waves for All Detectors

7. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors7 Bar Network: Int’l Gravitational Event Collaboration Network of the 5 bar detectors almost parallel ALLEGRO NFS-LSUhttp://gravity.phys.lsu.edu AURIGA INFN-LNLhttp://www.auriga.lnl.infn.it NIOBE ARC-UWAhttp://www.gravity.pd.uwa.edu.au EXPLORER INFN-CERN http://www.roma1.infn.it/rog/rogmain.html NAUTILUS INFN-LNF

8. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors8 CERN RE 5 LNF INFN MiniGrail Courtesy E. Coccia

9. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors9 AURIGA 2 nd run @ 4K: upgrades & results new mechanical suspensions: attenuation > 360 dB at 1 kHz FEM modelled new capacitive transducer: two-modes (1 mechanical+1 electrical) optimal mass new amplifier: double stage SQUID new data analysis: C++ object oriented code frame data format Bandwidth: noise floor below 5x10 -21 Hz -1/2 on a 100 Hz band Stationary gaussian behaviour: few spurious event/h after anticoincidence veto with 20 ms all band electromagnetic glitches Courtesy M. Cerdonio

10. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors10 New Generation of “Free- Mass” Detectors Now Online suspended mirrors mark inertial frames antisymmetric port carries GW signal Symmetric port carries common-mode info Intrinsically broad band and size-limited by speed of light.

11. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors11 The International Interferometer Network LIGO Simultaneously detect signal (within msec) detection confidence locate the sources decompose the polarization of gravitational waves GEO Virgo TAMA AIGO

12. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors12 LIGO (Washington) (4-km and 2km) LIGO (Louisiana) (4-km) The Laser Interferometer Gravitational-Wave Observatory Funded by the National Science Foundation; operated by Caltech and MIT; the research focus for more than 500 LIGO Scientific Collaboration members worldwide.

13. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors13 GEO 600 (Germany) 600-m Virgo (Italy) 3-km Interferometers in Europe

14. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors14 TAMA 300 (Japan) (300-m) AIGO (Australia) (80-m, but 3-km site) Interferometers in Asia, Australia

15. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors15 Spacetime is Stiff! => Wave can carry huge energy with miniscule amplitude! h ~ (G/c 4 ) (E NS /r)

16. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors16 Some of the Technical Challenges Typical Strains < 10 -21 at Earth ~ 1 hair’s width at 4 light years Understand displacement fluctuations of 4-km arms at the millifermi level (1/1000 th of a proton diameter) Control arm lengths to 10 -13 meters RMS Detect optical phase changes of ~ 10 -10 radians Hold mirror alignments to 10 -8 radians Engineer structures to mitigate recoil from atomic vibrations in suspended mirrors

17. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors17 What Limits Sensitivity of 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

18. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors18 Time Line First Science Data Inauguration 1999 3Q 4Q 2000 1Q 2Q 3Q 4Q 2001 1Q 2Q 3Q 4Q 2002 1Q 2Q 3Q 4Q 2003 1Q 2Q 3Q 4Q E1 Engineering E2E3E4E5E6E7E8E9 S1 Science S2S3 First Lock Full Lock all IFO's 10 -17 10 -18 10 -19 10 -20 strain noise density @ 200 Hz [Hz -1/2 ] 10 -21 Runs 10 -22 E10

19. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors19 Vibration Isolation Systems »Reduce in-band seismic motion by 4 - 6 orders of magnitude »Little or no attenuation below 10Hz »Large range actuation for initial alignment and drift compensation »Quiet actuation to correct for Earth tides and microseism at 0.15 Hz during observation HAM Chamber BSC Chamber

20. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors20 Seismic Isolation – Springs and Masses damped spring cross section

21. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors21 Core Optics Suspension and Control Shadow sensors & voice-coil actuators provide damping and control forces Mirror is balanced on 30 micron diameter wire to 1/100 th degree of arc Optics suspended as simple pendulums

22. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors22 Feedback & Control for Mirrors and Light Damp suspended mirrors to vibration-isolated tables »14 mirrors  (pos, pit, yaw, side) = 56 loops Damp mirror angles to lab floor using optical levers »7 mirrors  (pit, yaw) = 14 loops Pre-stabilized laser »(frequency, intensity, pre-mode-cleaner) = 3 loops Cavity length control »(mode-cleaner, common-mode frequency, common-arm, differential arm, michelson, power-recycling) = 6 loops Wave-front sensing/control »7 mirrors  (pit, yaw) = 14 loops Beam-centering control »2 arms  (pit, yaw) = 4 loops

23. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors23 Suspended Mirror Approximates a Free Mass Above Resonance Data taken using shadow sensors & voice coil actuators Blue: suspended mirror XF Cyan: free mass XF

24. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors24 Despite a few difficulties, science runs started in 2002.

25. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors25 LIGO Science Runs S1: 17 days in Aug-Sep 2002 »3 LIGO interferometers in coincidence with GEO600 and ~2 days with TAMA300 S2: Feb 14 – Apr 14, 2003 »3 LIGO interferometers in coincidence with TAMA300 S3: Oct 31, 2003 – Jan 9, 2004 »3 LIGO interferometers in coincidence with periods of operation of TAMA300, GEO600 and Allegro S4: Feb 22 – Mar 23, 2005 »3 LIGO interferometers in coincidence with GEO600, Allegro, Auriga

26. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors26 Binary Neutron Stars: S1 Range Image: R. Powell

27. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors27 Binary Neutron Stars: S2 Range Image: R. Powell S1 Range

28. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors28 Interferometer Strain Sensitivity

29. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors29 Science Analysis Searches for periodic sources, such as neutron stars Searches for compact-binary inspirals, e.g., neutron stars, black holes, MACHOs Searches for burst sources »Waveforms may be unknown or poorly known »Non-triggered search »Triggered search(e.g., supernova or GRB triggers) Stochastic waves of cosmological or astrophysical origin

30. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors30 LIGO Search Papers (as of 9May05) S1: “Setting upper limits on the strength of periodic gravitational waves using the first science data from the GEO600 and LIGO detectors”, Phys. Rev. D 69, 082004 (2004) “First upper limits from LIGO on gravitational wave bursts”, Phys. Rev. D 69, 102001 (2004) “Analysis of LIGO data for gravitational waves from binary neutron stars”, Phys. Rev. D 69, 122001 (2004) “Analysis of first LIGO science data for stochastic gravitational waves”, Phys. Rev. D 69, 122004 (2004) S2: “Limits on gravitational wave emission from selected pulsars using LIGO data”, Phys. Rev. Lett. 94, 181103 (2005). “A search for gravitational waves associated with the gamma ray burst GRB030329 using the LIGO detectors”, gr-qc/0501068 “Upper limits on gravitational wave bursts from LIGO’s second science run”, gr-qc/0505029

31. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors31 Binary Neutron Stars: Initial LIGO Target Range Image: R. Powell S2 Range

32. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors32 Future Plans for Terrestrial Detectors Improve reach of initial LIGO to run 1 integrated triple-coincidence year at design sensitivity Virgo has made steady progress in commissioning, due to come on line in ~ 1 year GEO600, TAMA300, striving for design sensitivity Resonant bars networking with interferometers for future runs Advanced LIGO technology under development, planning toward a detector construction start for FY2008

33. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors33 What’s next? Advanced LIGO… Major technological differences between LIGO and Advanced LIGO Initial Interferometers Advanced Interferometers Open up wider band Reshape Noise Quadruple pendulum: Silica optics, welded to silica suspension fibers Advanced interferometry Signal recycling Active vibration isolation systems High power laser (180W) 40kg

34. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors34 Binary Neutron Stars: AdLIGO Range Image: R. Powell LIGO Range

35. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors35 …and opening a new channel with a detector in space. Planning underway for space-based detector, LISA, to open up a lower frequency band ~ 2013-ish

36. LIGO-G050250-00-W Raab: Status of Gravitational Wave Detectors36 Summary We are currently experiencing a rapid advance in the sensitivity of searches for gravitational waves Elements of world-wide networks of interferometers and bars are operating The near future will see the confrontation of theory with many fine observational results