Gravitational wave astronomy a facilities overview Barry C

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

Towards Detection of Gravitational Waves § From LISA Concept § From Bars Demonstrations Mission Bars with Increased Bandwidth Spheres § From Interferometers Advanced Interferometers Generation (QND) Detectors § From 6 Mpc (NN inspiral) § From Upper Limits § From Generic Searches § From Single Detectors 13 -Jan-05 Next 200 Mpc and then beyond Searches Detections Searches with Specified Waveforms Global Networks AAS - Barish 2

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-05 AAS - Barish 3

LISA The three LISA spacecraft will be placed in orbits that form a triangular formation with center 20 o behind the Earth 13 -Jan-05 AAS - Barish 4

LISA Each spacecraft will be in an Earth-like orbit around the Sun and the triangle appears to rotate through the year. 13 -Jan-05 AAS - Barish 5

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. 13 -Jan-05 AAS - Barish 6

LISA The diagram shows the sensitivity bands for LISA and LIGO 13 -Jan-05 AAS - Barish 7

LISA Massive Black Hole Binary Inspirals A coalescence of two 105, 106 and 107 solar mass black holes 13 -Jan-05 AAS - Barish 8

Resonant Bar Detectors Mini. Grail The Netherlands Auriga, Italy Allegro USA Schenberg Brazil Nautilus, italy Explorer Switzerland 13 -Jan-05 AAS - Barish Niobe Australia 9

The resonant transducer The displacement of the secondary oscillator modulates a dc electric or magnetic field or the frequency of a s. c. cavity x. M 13 -Jan-05 AAS - Barish xm 10

Sensitivity of Resonant Detectors Noise in the detector Extrinsic: Seismic noise mechanical filter Intrinsic: Thermal noise cool detector amplifier noise SQUID amplifier transducer 13 -Jan-05 AAS - Barish 11

AURIGA LHe 4 vessel Al 2081 holder Electronics wiring support Main Attenuator Sensitive bar Thermal Shield Compression Spring 13 -Jan-05 AAS - Barish Transducer 12

AURIGA 2 nd 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 x 10 -19 in both situation Best result obtained when spurious lines fade out Bandwidth: h < 5 x 10 -21 Hz-1/2 within ~100 Hz band (noise floor) 13 -Jan-05 AAS - Barish 13

Network of Resonant Bars Allegro Explorer Auriga Nautilus IGEC Network 13 -Jan-05 AAS - Barish Niobe 14

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. 13 -Jan-05 AAS - Barish 15

IGEC coincidence search Upper Limit on the Rate of gravitational waves bursts from the GALACTIC CENTER random 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 13 -Jan-05 DE ~ 0. 02 M⊙ converted @ 10 kpc - Barish [P. Astone, et al. AAS Phys. Rev. D 68 (2003) 022001] 16

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 ? ? ? Number of events Direction of Galactic Disc Sidereal hours ROG Coll. : CQG 19, 5449 (2002) L. S. Finn: CQG 20, L 37 (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 ! 13 -Jan-05 AAS - Barish 17

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 13 -Jan-05 AAS - Barish 18

TAMA Japan 300 m Interferometer Detectors LIGO Louisiana 4000 m Virgo Italy 3000 m GEO Germany 600 m AIGO Australia future LIGO Washington 2000 m & 4000 m 13 -Jan-05 AAS - Barish 19

Network of Interferometers LIGO GEO decompose the polarization of detection locate the confidence sources gravitational waves 13 -Jan-05 AAS - Barish Virgo TAMA AIGO 20

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-05 AAS - Barish 21

Evolution of LIGO Sensitivity 13 -Jan-05 AAS - Barish 22

LIGO Science Has Begun Three Science Runs (S 1 --S 3) interspersed with commissioning S 1 run: Primarily methods papers - 17 days (Aug - Sep 2002) Four S 1 astrophysical searches published (Phys. Rev. D 69, 2004): § Inspiraling neutron stars 122001 § Bursts 102001 § Known pulsar (J 1939+2134) with GEO 082004 § Stochastic background 122004 S 2 run: S 2 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) S 3 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 S 2, S 3 papers under review by collaboration 13 -Jan-05 AAS - Barish 23

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-05 AAS - Barish 24

Directed searches NO DETECTION EXPECTED at present sensitivities Crab Pulsar Limits of detectability for rotating NS with equatorial ellipticity e = d. I/Izz: 10 -3 , 10 -4 , 10 -5 @ 8. 5 kpc. PSR J 1939+2134 13 -Jan-05 AAS - Barish 1283. 86 Hz 25

Summary of S 2 results limits on strain Crab pulsar S 1 J 1939+2134 J 1910 – 5959 D: Marginalized Bayesian PDF for h PDF h 95 S 2 0 strain Red dots: pulsars are in globular clusters - cluster dynamics hide intrinsic spindown properties Blue dots: field pulsars for which spin-downs are known h 0 = 1. 7 x 10 -24 13 -Jan-05 1 AAS - Barish 26

Summary S 2 results - ellipticity limits Best upper-limits: • J 1910 – 5959 D: h 0 < 1. 7 x 10 -24 • J 2124 – 3358: < 4. 5 x 10 -6 How far are S 2 results from spindown limit? Crab: ~ 30 X LIGO upper-limits from hmax J 1939+2134 S 1 S 2 EM spin-down upper-limits 13 -Jan-05 AAS - Barish Red dots: pulsars are in globular clusters - cluster dynamics hide intrinsic spin-down properties Blue dots: field pulsars for which spin-downs are known 27

Advanced LIGO Multiple Suspensions Active Seismic Sapphire Optics Higher Power Laser 13 -Jan-05 AAS - Barish 28

Advanced LIGO 2007 + Enhanced Systems • laser • suspension • seismic isolation • test mass Rate Improvement ~ 104 + narrow band optical configuration 13 -Jan-05 AAS - Barish 29

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 !! 13 -Jan-05 AAS - Barish 30