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LISA

Gravitational wave astronomy: a facilities overview Barry C. Barish Caltech AAS San Diego 13-Jan-05. LISA. Towards Detection of Gravitational Waves. From LISA Concept Demonstrations Mission From Bars Bars with Increased Bandwidth Spheres

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LISA

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  1. Gravitational wave astronomy: a facilities overviewBarry C. BarishCaltechAASSan Diego13-Jan-05 LISA

  2. Towards Detection of Gravitational Waves • From LISA Concept Demonstrations Mission • From Bars Bars with Increased Bandwidth Spheres • From Interferometers Advanced Interferometers Next Generation (QND) Detectors • From 6 Mpc (NN inspiral) 200 Mpc and then beyond • From Upper Limits Searches Detections • From Generic Searches Searches with Specified Waveforms • From Single Detectors Global Networks AAS - Barish

  3. Gravitational Waves in Space LISA Three spacecraft, each with a Y-shaped payload, form an equilateral triangle with sides 5 million km in length. AAS - Barish

  4. LISA The three LISA spacecraft will be placed in orbits that form a triangular formation with center 20o behind the Earth AAS - Barish

  5. LISA Each spacecraft will be in an Earth-like orbit around the Sun and the triangle appears to rotate through the year. AAS - Barish

  6. LISA 'Y'-shaped payload has two identical optical assemblies with transmit/receive telescopes and optical benches carrying the inertial sensor and the interferometry optics. The inertial sensor consists of a free-falling proof mass inside a reference housing, which is fixed to the spacecraft. AAS - Barish

  7. LISA The diagram shows the sensitivity bands for LISA and LIGO AAS - Barish

  8. LISA Massive Black Hole Binary Inspirals A coalescence of two 105, 106 and107 solar mass black holes AAS - Barish

  9. Resonant Bar Detectors MiniGrail The Netherlands Auriga, Italy Allegro USA Future Schenberg Brazil Nautilus, italy Future Explorer Switzerland Niobe Australia AAS - Barish

  10. The resonant transducer The displacement of the secondary oscillator modulates a dc electric or magnetic field or the frequency of a s.c. cavity xM xm AAS - Barish

  11. Sensitivity of Resonant Detectors • Noise in the detector • Extrinsic: Seismic noise  mechanical filter • Intrinsic: Thermal noise  cool detector • amplifier noise  SQUID amplifier amplifier transducer AAS - Barish

  12. LHe4 vessel Al2081 holder Electronics wiring support Main Attenuator Thermal Shield Sensitive bar Compression Spring Transducer AURIGA AAS - Barish

  13. AURIGA 2nd run: preliminary results * * * * * * _Experimental results _ Expected sensitivity Spurious lines (x) are related to environmental noise but do not affect significantly the burst sensitivity e.g., for a 1 ms sin-gaussian pulse: hmin≈ 3 x10-19 in both situation Best result obtained when spurious lines fade out Bandwidth: h < 5x10-21 Hz-1/2 within ~100 Hz band (noise floor) AAS - Barish

  14. Network of Resonant Bars Allegro Auriga Explorer Nautilus Niobe IGEC Network AAS - Barish

  15. International Gravitational Event Collaboration (IGEC) • ALLEGRO,AURIGA,EXPLORER, NAUTILUS, and NIOBE 1997-2000. • The search for burst waves at resonant frequency ~ 900 Hz. • The detectors nearly parallel to maximize coincident sensitivity. • Candidate events at SNR > 3-5 (~background events 100/day) • Data exchanged: peak amplitude, time of event and uncertainties. • Threshold equivalent to ~0.1 M⊙ converted into a gravitational wave millisecond burst at a distance of 10 kpc. • The accidental coincidence rate over 1 sec interval (e.g. bandwidth of 1 Hz) was ~ few/week two-fold and ~few/century three-fold. • Time resolution not sufficient to resolve incident wave direction, no directional search has been applied. • No evidence for grav wave bursts was found. AAS - Barish

  16. IGEC coincidence search Upper Limit on the Rateof gravitational waves bursts from the GALACTIC CENTERrandom arrival times and amplitude  search threshold h Final results rate [y –1] The Area above the blue curve is excluded with a coverage > 90% search threshold h h~ 2 10-18 DE ~ 0.02 M⊙ converted @ 10 kpc AAS - Barish [P. Astone, et al. Phys. Rev. D68 (2003) 022001]

  17. EXPLORER-NAUTILUS 2001 During 2001 EXPLORER and NAUTILUS were the only two operating resonant detectors, with the best ever reached sensitivity. An algorithm based on energy compatibility of the event was applied to reduce the “background” Excess ??? Direction of Galactic Disc Number of events Sidereal hours ROG Coll.: CQG 19, 5449 (2002) L.S.Finn: CQG 20, L37 (2003) P.Astone, G.D’Agostini, S.D’Antonio: CQG Proc. Of GWDAW 2002, gr-qc/0304096 E. Coccia ROG Coll.:CQG Proc. Of GWDAW 2002 ROG Coll.: gr-qc/0304004 New data is needed with more antennas in coincidence ! AAS - Barish

  18. Resonant Spheres The future?? TIGA • Much larger cross-section than a bar of the same resonant frequency (up to 70 x) • Omni-directional: Allows for the determination of direction and polarization • Require 6 transducers • Hollow spheres could allow a choice of cross-sections and frequencies AAS - Barish

  19. Interferometer Detectors LIGO Louisiana 4000m TAMA Japan 300m Virgo Italy 3000m GEO Germany 600m AIGO Australia future LIGO Washington 2000m & 4000m AAS - Barish

  20. Network of Interferometers LIGO Virgo GEO TAMA AIGO decompose the polarization of gravitational waves detection confidence locate the sources AAS - Barish

  21. Astrophysical Sources • 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” AAS - Barish

  22. Evolution of LIGO Sensitivity AAS - Barish

  23. LIGO Science Has Begun Three Science Runs(S1--S3) interspersed with commissioning S1 run: Primarily methods papers - 17 days (Aug - Sep 2002)Four S1 astrophysical searches published (Phys. Rev. D 69, 2004): • Inspiraling neutron stars122001 • Bursts102001 • Known pulsar (J1939+2134) with GEO082004 • Stochastic background122004 S2 run:S2 analyses are mostly complete - 59 days (Feb - April 2003) • Results presented at APS 2004 Spring Meeting • GR-17 (Dublin) • Gravitational Wave Data Analysis Workshop (GWDAW) in Annecy, France (December 2004) S3 run: Analysis is in full swing - 70 days (Oct 2003 – Jan 2004) • Analysis is in full swing; preliminary results becoming available for GWDAW meeting in Annecy, France A number of drafts of S2, S3 papers under review by collaboration AAS - Barish

  24. Detection of Periodic Sources • Pulsars in our galaxy: “periodic” • search for observed neutron stars • all sky search (computing challenge) • r-modes • Frequency modulation of signal due to Earth’s motion relative to the Solar System Barycenter, intrinsic frequency changes. • Amplitude modulation due to the detector’s antenna pattern. AAS - Barish

  25. PSR J1939+2134 1283.86 Hz Directed searches NO DETECTION EXPECTED at present sensitivities Crab Pulsar Limits of detectability for rotating NS with equatorial ellipticity e = dI/Izz: 10-3 , 10-4 , 10-5 @ 8.5 kpc. AAS - Barish

  26. Crab pulsar Marginalized Bayesian PDF for h S1 J1939+2134 S2 1 PDF 0 J1910 – 5959D: h0 = 1.7 x 10-24 h95 strain Summary of S2 resultslimits on strain Red dots: pulsars are in globular clusters - cluster dynamics hide intrinsic spin-down properties Blue dots: field pulsars for which spin-downs are known AAS - Barish

  27. LIGO upper-limits from hmax J1939+2134 S1 S2 EM spin-down upper-limits Summary S2 results - ellipticity limits • Best upper-limits: • J1910 – 5959D: h0 < 1.7 x 10-24 • J2124 – 3358:  < 4.5 x 10-6 • How far are S2 results from spin-down limit? Crab: ~ 30X Red dots: pulsars are in globular clusters - cluster dynamics hide intrinsic spin-down properties Blue dots: field pulsars for which spin-downs are known AAS - Barish

  28. Advanced LIGO Multiple Suspensions Active Seismic Sapphire Optics Higher Power Laser AAS - Barish

  29. Advanced LIGO 2007 + • Enhanced Systems • laser • suspension • seismic isolation • test mass Rate Improvement ~ 104 + narrow band optical configuration AAS - Barish

  30. Conclusions • Sensitivity toward gravitational wave detection is improving on many fronts and this will continue into the future • Improved upper limits are being set for all major sources -- binary inspirals, periodic sources, burst sources and stochastic background • Transition is being made from data analysis oriented toward upper limit setting to analysis aimed at detection • Data exchange and joint data analysis between detector groups is improving our ability to make detections • Need specific waveforms to improve search sensitivities! • Hopefully, detections will be made soon !! AAS - Barish

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