Gravitational Waves: Current and future experiments

Transcription

1 Munich 5-9, September Gravitational Waves: Current and future experiments Kazuaki Kuroda ICRR, The University of Tokyo

2 Related talks in parallel session yesterday Well-balanced introductory talk by Laura Cadonati (U Mass) Noise and signal by Giovanni Andrea Prodi (U Trento) LCGT status by Shinji Miyoki (ICRR, UT) Starving field of GW by Bruce Allen (MPI, Hannover) GW from rotating star by Andrzej Krolak (Inst. Math, Polish Academy of Science) ET by Harald Lueck (MPI, AEI) Bar detector response to cosmic particle by Francesco Ronga (INFN) A laser gryo by Angela Virgilio (INFN-Pisa)

3 Introduction: Generation of Gravity wave Gravity waves are produced dynamic motion of massive terrestial objects. Here consider the radiation by simple rotating equal masses Radiation formula of EM Luminosity = (2/3c 3 ) e 2 a 2 Radiation from Mass dipole moment = 0 Radiation of mass quadrupole moment is the lowest term of gravity wave Gravity wave luminosity = (G/5c 5 )( I ) 2 I = I jk I jk, I jk = Σm A (x Aj x Ak -1/3δ jk r A2 ) I jk : the reduced quadrupole moment Introductory talk by Laura & spinning star by A Krolak

4 Introduction: Target GW Sources 1. Coalescence of neutron star binaries 2. Coalescence of black hole binaries 3. Core collapse of massive stars 4. Existing neutron star binaries in our Galaxy PSR B PSR B PSR J PSR J PSR J chirp signal -300Hz coalescence quasi-mode oscillation -1kHz msec

5 Intro: Detection of gravity wave by resonant antennae J. Weber started to make practical detector in late of 1960s Gravity plane wave h ij = h 11 h h 21 h GR is being tested as in Angela s talk Disk type: Resonant frequency could be changed by making slits Bar type: Resonant frequency was determined by the length of the bar Tidal force of gravity wave causes elastic vibration of eigen mode, which can be detected by sensitive transducer. Thermal noise of vibration is reduced by lowering the temperature.

6 NAUTILUS - INFN Frascati V p Detectable: Galactic burst with converted in GWs 10 6 M sun c 2 Antenna M R p C d Readout: Resonant capacitive transducer & Dc SQUID amplifier Phys.Rev.Lett. 91:111101, Peak strain sensitivity Hz Displacement sensitivity m Hz Unprecedented: World Record By the courtesy of Eugenio

7 Nautilus as acoustic particle detector See presentation file of Francesco Interaction of a particle with a bar: ionization energy lost is converted in thermal heating and therefore pressure wave. The detection mechanism is quite simple, no threshold in β calorimetric measurement Nautilus is able to detect energy releases as low as 10-7 ev (10-26 J) by measuring the excitation of the longitudinal mode of Vibration. Nautilus is equipped with streamer tubes particle detectors Cosmic rays: observed Exotic form of matter: observable Upper limit for nuclearite flux from the Rome GW resonant detectors Phys.Rev. D47: , 1993 Cosmic rays observed by NAUTILUS Phys.Rev.Lett. 84:14-17, Detection of high energy cosmic rays with NAUTILUS Astropart.Phys. 30: , 2008.

8 Intro: Detection of gravity wave by Interferometer This is also shown by Laura using Fabry-Perot Interferometer Metric perturbation g ij =η ij + h ij h ij = is detected by Michelson type laser interferometer z wave propagation Gravity plane wave h 11 h h 21 h Typical amplitude h ~ Mirror Y Mirror X Laser Beam Splitter Photo detector Light speed of propagation differs for each arms of Interferometer ΔL/L h/2 Phase difference at BS is detected by power change of the photodiode

9 Intro: Noise of Current Interferometers Mirror Substrate thermal Suspension thermal Coating thermal Laser pressure Anti-vibration system Sensitivity limited only by fundamental noise sources Seismic noise sensitivity seismic Photon counting Suspension thermal Mirror thermal Laser power Frequency Blood sweat and tears in reducing noise is summarized in Giovanni s talk

10 AURIGA Current detectors in the World GEO HF LIGO(I) Hanford ET (planed) TAMA/CLIO LCGT (under construction) Adv. LIGO (under construction) Virgo Adv. Virgo (under construction) LIGO(I) Livingston Nautilus LIGO-Australia (budget request) A network of detectors is indispensable to position the source.

11 Necessity of more sensitive detectors The present detectors such as LIGO (USA), VIRGO (French-Italian), GEO (Germany-England) and TAMA/CLIO (Japan) have sensitivity to catch GW events occurring at most 30Mpc. Since the occurrence rate of the coalescence of BNS is estimated to be 10-5 for matured galaxy per year and there are 0.01 galaxies for 1 cubic Mpc, it takes roughly 300 years to catch one event. Advanced detectors are under construction to detect events occurring at around 200Mpc, which makes possible to detect at least a few events of BNS coalescence in a year.

12 LIGO project and Advanced LIGO One interferometer with 4 km Arms, One with 2 km Arms Initial LIGO timeline Construction started in 1994 First data-colletction (S1) 2002 Design Sensitivity Achieved 2005 Enhanced LIGO (S6) One interferometer with 4 km Arms

13 Sensitivity improvement in Initial LIGO ( )

14 Efforts of Enhanced LIGO Estimation of Noise Increased laser power 10 W -> W EOM Faraday Isolator Thermal lensing Radiation Pressure DC readout OMC Detector in Vacuum

15 Scope of Advanced LIGO Advanced LIGO Monolithic suspension TCS performance New isolation system

16 Virgo project 8m tall Italian-French Collaboration Construction completed in 2003 Final configuration in 2005 Data-taking started in 2006 (VSR1) ended in 2007 with LSC Virgo+ (VSR 2, S6) ended in 2010 Typical features: Located at Cascina in Pisa 3km baseline length Fabry-Perot Michelson Interferometer Ultra-low frequency isolation system Low frequency isolation system characterizes the Virgo interferometer

17 Sensitivity Improvement

18 From Virgo+ to Advanced Virgo High power laser: 25 W (Virgo+) -> 200 W Input mode cleaner Improved TCS (thermal compensation system) Control electronics New optics Heavier mirror mass Monolithic fused silica suspension Upgraded seismic isolation system

19 Current design of Advanced Virgo 40 kg test masses large spot size 1) Funded by INFN/CNRS (and contributed by NIKHEF) in Dec ) Procurements and parts construction started 3) Installation to start at the end of the year 4) Acceptance in 2015 high power fiber laser dual recycled DC readout

20 GEO600 project GEO optical Layout Power Recycling Mirror T=0.09% End mirrors with Electro-static actuators Output mode cleaner Signal Recycling Mirror T=10% DC readout GEO is an observing instrument and a prototype for new technologies 'Advanced techniques' of GEO: Monolothic suspensions (since ~10 years) Electro-static actuators Signal recycling Squeezing (since 2010)

21 Squeezer Installation in May 2010 Squeezing light is introduced from signal port to reduce shot noise. 3.5dB Improvement has been achieved and 4dB more is expected in 2011

22 GEO600 Science Times since 2006 LSC-s5: 421 days, 90% (duty factor in 24/7) Astrowatch Nov July 2009: 522 days, 86% LSC-s6d: 60 days, 88% VSR4/S6e, Virgo/GEO summer run 3.June 5.September % 22

23 GEO-HF sensitivity Next Step Commissioning Squeezing: automatic alignment, 4+dB Intermediate freq. noise reduction. 30W main laser, new IMC mirrors, thermal compensation for BS, ->circulating light power increase Data taking night/weekend mode Longer periods / higher duty cycle as GEO-HF progresses Strain [ 1 /sqrt(hz)] Frequency [Hz]

24 TAMA/CLIO TAMA is a 300 m baseline Fabry-Perot Michelson Interferometer with power recycling and achieved the best sensitivity and long observation run earlier than any other long baseline interferometers by R&D are being conducted for advanced interferometer techniques for LCGT. TAMA in Mitaka, Tokyo CLIO is a 100 m cryogenic locked Fabry-Perot interferometer placed underground at Kamioka mine. Thermally limited sensitivity was achieved in 2009 by cooling mirrors down to 10 K. It is a test bench for cryogenic part of LCGT. CLIO underground at Kamioka

25 Location of LCGT LCGT is planed to be built underground at Kamioka, where the prototype CLIO detector is placed. Full explanation was given by Shinji

26 LCGT design Power recycled Fabry-Perot Michelson interferometer with Resonant-side-band extraction Double floor isolation system Mounted above cryostat 75 w Cryostat for main mirrors PTC Heat link Main mirror

27 R&D results by TAMA and CLIO for LCGT TAMA in 2008 (improved after installation of SAS) 300 m arm length CLIO at cryo temperature, 2010/3/7 100 m arm length LIGO 4 km CLIO limit by room temperature LCGT design, 3 km

28 LIGO-Australia A set of Advanced LIGO is planed to be installed at Gingin north of Perth in Western Australia (AIGO project of ACIGA consortium, InDIGO, China) *) Funding is being requested to Australian government, the result of which will be disclosed, soon. *) NSF has approved If realized, the positioning accuracy of sources becomes much improved

29 LIGO-India InDIGO (since 2009)Roadmap workshop in Delhi at University of Delhi, December 2010 Funding for 3m prototype interferometer at the Tata Institute for Fundamental Research Created an Indo-US Center for GWs, funding awarded Proposing to participate in LIGO-Australia as a major partner (15%) Possible alternative of the case of disapproval of LIGO-Australia

30 Einstein Telescope Given by Harald

31 GWIC roadmap of ground based detectors Will be organized as LIGO-Australia or LIGO-India

32 L I S A LISA is a joint NASA-ESA space mission of interferometer to see gravity wave events more remotely and more frequently. - Frequency band: 0.03mHz-0.1Hz, abundant science objects - 5 million km baseline length - LISA Pathfinder will be launched in 2013 for the test of technologies for LISA Orbital motion of LSIA satellites Preparation of LISA Pathfinder

33 DECIGO DECIGO: Fabry-Perot space interferometer works in frequencies from Hz 1000 km Objective: 1)Direct observation of the beginning of The Universe 2) Measuring the acceleration of the Universe DECIGO Pathfinder tests the technologies required to realize DECIGO Will be nominated by the small science spacecraft series run by JAXA/ISAS

34 AstroWatch recommended by GWIC AURIGA and NAUTILUS in operation as an "astrowatch" until LIGO/Virgo resume operation after upgrade GEO-HF enters this operation as soon as possible AURIGA & NAUTILUS continously on the air > 95 % with noise close to Gaussian (~ 20 outliers/day at SNR>6) until LIGO/Virgo resume operation burst sensitivity h rss ~ Hz -1/2 h burst ~ 2x10-19 or AUNA: astrowatch of AURIGA & NAUTILUS

35 excercise in recovering injected bursts of M solar with coherent wavebursts analysis; bursts of random ploarization randomly injected in the Galaxy accordingly to the star density; injections over 1day of AUNA data detection efficiency vs distance Distribution in the Galactic plane of the injections (colour) and of the recovered signals (black)

36 Summary By the first generation detectors of LIGO, GEO, Virgo, TAM/CLIO, we are not in success to catch GW This is represented as starving, suffering from lack of signal, compared with wealthy astronomers by Bruce Allen By two talks in yesterday parallel session; EM follow-up by Marica Branchesi (U Urbino) and first joint analysis with ANTARES by Irene Palma (MPI, AEI) show dynamic approach for signal This situation is rescued only by operating more sensitive detectors such as Advanced LIGO, Advanced Virgo, and LCGT, which is firmly confirmed by the previous talk of Alan Weinstein We aren t spiritually starving. We hope that ET will be funded soon and LISA heads along its original strategy