Gravitational wave astronomy: a facilities overview Barry C. Barish Caltech AAS San Diego 13-Jan-05 LISA

13-Jan-05AAS - Barish2 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

13-Jan-05AAS - Barish3 Gravitational Waves in Space LISA Three spacecraft, each with a Y-shaped payload, form an equilateral triangle with sides 5 million km in length.

13-Jan-05AAS - Barish4 LISA The three LISA spacecraft will be placed in orbits that form a triangular formation with center 20 o behind the Earth

13-Jan-05AAS - Barish5 LISA Each spacecraft will be in an Earth-like orbit around the Sun and the triangle appears to rotate through the year.

13-Jan-05AAS - Barish6 '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. LISA

13-Jan-05AAS - Barish7 LISA The diagram shows the sensitivity bands for LISA and LIGO

13-Jan-05AAS - Barish8 LISA A coalescence of two 10 5, 10 6 and 10 7 solar mass black holes

13-Jan-05AAS - Barish9 Explorer Switzerland Allegro USA Schenberg Brazil MiniGrail The Netherlands Niobe Australia Nautilus, italy Auriga, Italy Resonant Bar Detectors

13-Jan-05AAS - Barish10 The resonant transducer xMxM xmxm The displacement of the secondary oscillator modulates a dc electric or magnetic field or the frequency of a s.c. cavity

13-Jan-05AAS - Barish11 Sensitivity of Resonant Detectors Noise in the detector Extrinsic: Seismic noise  mechanical filter Intrinsic: Thermal noise  cool detector amplifier noise  SQUID amplifier transducer amplifier

13-Jan-05AAS - Barish12 AURIGA Transducer Electronics wiring support LHe4 vessel Al2081 holder Main Attenuator Compression Spring Thermal Shield Sensitive bar

13-Jan-05AAS - Barish13 AURIGA Bandwidth: h < 5x Hz -1/2 within ~100 Hz band (noise floor) 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: h min ≈ 3 x in both situation Best result obtained when spurious lines fade out _ Experimental results _ Expected sensitivity * * * ** * 2 nd run: preliminary results

13-Jan-05AAS - Barish14 Network of Resonant Bars Allegro Explorer Auriga Nautilus Niobe IGEC Network

13-Jan-05AAS - Barish15 International Gravitational Event Collaboration (IGEC)  ALLEGRO,AURIGA,EXPLORER, NAUTILUS, and NIOBE  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.

13-Jan-05AAS - Barish16 rate [y –1 ] search threshold h h ~  E ~ 0.02 M ⊙ 10 kpc Upper Limit on the Rate of gravitational waves bursts from the GALACTIC CENTER random arrival times and amplitude  search threshold h The Area above the blue curve is excluded with a coverage > 90% [ P. Astone, et al. Phys. Rev. D68 (2003) ] IGEC coincidence search Final results

13-Jan-05AAS - Barish17 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” EXPLORER-NAUTILUS 2001 Sidereal hours Number of events 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/ E. Coccia ROG Coll.:CQG Proc. Of GWDAW 2002 ROG Coll.: gr-qc/ New data is needed with more antennas in coincidence ! Excess ??? Direction of Galactic Disc

13-Jan-05AAS - Barish18 Resonant Spheres 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 The future?? TIGA

13-Jan-05AAS - Barish19 Interferometer Detectors LIGO Louisiana 4000m TAMA Japan 300m Virgo Italy 3000m GEO Germany 600m AIGO Australia future LIGO Washington 2000m & 4000m

13-Jan-05AAS - Barish20 Network of Interferometers LIGO detection confidence GEO Virgo TAMA AIGO locate the sources decompose the polarization of gravitational waves

13-Jan-05AAS - Barish21 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”

13-Jan-05AAS - Barish22 Evolution of LIGO Sensitivity

13-Jan-05AAS - Barish23 LIGO Science Has Begun S1 run: Primarily methods papers - 17 days (Aug - Sep 2002) Four S1 astrophysical searches published (Phys. Rev. D 69, 2004):  Inspiraling neutron stars  Bursts  Known pulsar (J ) with GEO  Stochastic background 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 Three Science Runs (S1--S3) interspersed with commissioning A number of drafts of S2, S3 papers under review by collaboration

13-Jan-05AAS - Barish24 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.

13-Jan-05AAS - Barish25 Directed searches NO DETECTION EXPECTED at present sensitivities PSR J Hz Limits of detectability for rotating NS with equatorial ellipticity  =  I/I zz : 10 -3, 10 -4, kpc. Crab Pulsar

13-Jan-05AAS - Barish26 Summary of S2 results limits on strain S1 J S2 J1910 – 5959D: h 0 = 1.7 x Crab pulsar Red dots: pulsars are in globular clusters - cluster dynamics hide intrinsic spin- down properties Blue dots: field pulsars for which spin-downs are known h 95 1 PDF 0 strain Marginalized Bayesian PDF for h

13-Jan-05AAS - Barish27 EM spin-down upper-limits LIGO upper-limits from h max J S1 S2 Summary S2 results - ellipticity limits Red dots: pulsars are in globular clusters - cluster dynamics hide intrinsic spin-down properties Blue dots: field pulsars for which spin-downs are known Best upper-limits: J1910 – 5959D: h 0 < 1.7 x J2124 – 3358:  < 4.5 x How far are S2 results from spin-down limit? Crab: ~ 30X

13-Jan-05AAS - Barish28 Advanced LIGO Active Seismic Multiple Suspensions Sapphire Optics Higher Power Laser

13-Jan-05AAS - Barish29 Advanced LIGO Enhanced Systems laser suspension seismic isolation test mass Rate Improvement ~ narrow band optical configuration

13-Jan-05AAS - Barish30 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 !!