The Status of Gravitational-Wave Detectors

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

2. 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 Raab: Status of Gravitational Wave Detectors

3. Different Frequency Bands of Detectors and Sources space terrestrial Audio band • EM waves are studied over ~20 orders of magnitude • (ULF radio -> HE  rays) • Gravitational Wave coverage over ~8 orders of magnitude • (terrestrial + space) Raab: Status of Gravitational Wave Detectors

4. Catching Waves FromOrbiting Black Holes and Neutron Stars Sketches courtesy of Kip Thorne Raab: Status of Gravitational Wave Detectors

5. Gravitational Waves the evidence Emission of gravitational waves Neutron Binary System – Hulse & Taylor PSR 1913 + 16 -- Timing of pulsars 17 / sec · · ~ 8 hr • Neutron Binary System • separated by 106 miles • m1 = 1.4m; m2 = 1.36m; e = 0.617 • Prediction from general relativity • spiral in by 3 mm/orbit • rate of change orbital period Raab: Status of Gravitational Wave Detectors

6. Basic Signature of Gravitational Waves for All Detectors Raab: Status of Gravitational Wave Detectors

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

8. CERN RE 5 MiniGrail LNF INFN Courtesy E. Coccia Raab: Status of Gravitational Wave Detectors

9. AURIGA 2nd 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 with20 ms all band electromagnetic glitches Courtesy M. Cerdonio Raab: Status of Gravitational Wave Detectors

10. 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. Raab: Status of Gravitational Wave Detectors

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

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

13. Interferometers in Europe GEO 600 (Germany) 600-m Virgo (Italy) 3-km Raab: Status of Gravitational Wave Detectors

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

15. Spacetime is Stiff! => Wave can carry huge energy with miniscule amplitude! h ~ (G/c4) (ENS/r) Raab: Status of Gravitational Wave Detectors

16. 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 (1/1000th 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 Raab: Status of Gravitational Wave Detectors

17. 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 Raab: Status of Gravitational Wave Detectors

18. 1999 2003 2002 2001 2000 4Q 3Q 2Q 2Q 2Q 2Q 4Q 4Q 4Q 4Q 1Q 1Q 1Q 1Q 3Q 3Q 3Q 3Q Full Lock all IFO's First Lock Inauguration strain noise density @ 200 Hz [Hz-1/2] 10-17 10-18 10-19 10-21 10-22 10-20 S1 S2 S3 Science E1 E2 E3 E4 E5 E6 E7 E8 E9 E10 Engineering Runs First Science Data Time Line Raab: Status of Gravitational Wave Detectors

19. 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 BSC Chamber HAM Chamber Raab: Status of Gravitational Wave Detectors

20. damped springcross section Seismic Isolation – Springs and Masses Raab: Status of Gravitational Wave Detectors

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

22. 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 Raab: Status of Gravitational Wave Detectors

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

24. Despite a few difficulties, science runs started in 2002. Raab: Status of Gravitational Wave Detectors

25. 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 Raab: Status of Gravitational Wave Detectors

26. Binary Neutron Stars:S1 Range Raab: Status of Gravitational Wave Detectors Image: R. Powell

27. Binary Neutron Stars:S2 Range S1 Range Raab: Status of Gravitational Wave Detectors Image: R. Powell

28. Interferometer Strain Sensitivity Raab: Status of Gravitational Wave Detectors

29. 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 Raab: Status of Gravitational Wave Detectors

30. LIGO Search Papers(as of 9May05) • “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) S1: 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 Raab: Status of Gravitational Wave Detectors

31. Binary Neutron Stars:Initial LIGO Target Range S2 Range Raab: Status of Gravitational Wave Detectors Image: R. Powell

32. 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 Raab: Status of Gravitational Wave Detectors

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

34. Binary Neutron Stars:AdLIGO Range LIGO Range Raab: Status of Gravitational Wave Detectors Image: R. Powell

35. …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 Raab: Status of Gravitational Wave Detectors

36. 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 Raab: Status of Gravitational Wave Detectors