1. Japanese Gravitational Wave Detectors: LCGT and DECIGO Frontiers in Optics 2009 Laser Science XXV Oct. 13, 2009 San Jose, USA Seiji Kawamura (NAOJ), LCGT Collaboration, DECIGO Working Group Sora

2. Outline  Roadmap  Ground-based detector TAMA300 CLIO LCGT  Space antenna DECIGO DECIGO Pathfinder

3. Roadmap of the Japanese GW detection 200 0 01020304050607080910111213141516171819202122232425262728 Ground-based ▲▲▲ Space ▲▲▲ TAMA CLIO LCGT DECIGO Pathfinder Pre-DECIGO DECIGO R&D Advanced LCGT

4. Ground-based Detector  TAMA300  CLIO  LCGT

5. 5 TAMA300 300 m power-recycled FP Michelson interferometer located on the NAOJ campus in Tokyo Project started 1995 Best sensitivity in world 2000-2002

6. 6 New Seismic Attenuation System Joint development with LIGO (Riccardo DeSalvo et al.) based on earlier Virgo concept Photo: Nikon

7. 100 m cryogenic prototype Differential FP interferometer located in the Kamioka mine in Gifu TAMA300 CLIO

8. Ground motion in Kamioka mine

9. Sensitivity of CLIO Frequency Displacement noise 1/√Hz Mirror suspension thermal noise --inversely proportional to f 2.5 Mirror thermal noise Thermal noise limit by eddy current damping between actuator magnets and metal solenoid holder --inversely proportional to f 2

10. 3km Underground at Kamioka Cryogenic mirrors LCGT

11. Goal Sensitivity of LCGT

12. Detection range of LCGT

13. LCGT in network L/H+L/L+V 50% L/H+L/L+V+LCGT 50% B. F. Schutz LIGO(H)+LIGO(L)+Virgo Coverage at 0.5 M.S.: 72% 3 detector duty cycle: 51% LIGO(H)+LIGO(L)+Virgo+LCGT Max sensitivity (M.S.): +13% Coverage at 0.5 M.S.: 100% 3 detector duty cycle: 82%

14. Organization LCGT: hosted by ICRR under MOU with NAOJ and KEK. LCGT collaboration: 118 members (92 domestic, 26 oversea members)

15. Funding Status  Proposal for the 2010 start did not go through.  We will submit a proposal for the 2011 start.  Application for the stimulus fund was turned down.

16. What is DECIGO? Deci-hertz Interferometer Gravitational Wave Observatory ( Kawamura, et al., CQG 23 (2006) S125-S131) Bridges the gap between LISA and terrestrial detectors Low confusion noise -> Extremely high sensitivity 10 -18 10 -24 10 -22 10 -20 10 -4 10 4 10 2 10 0 10 -2 Frequency [Hz] Strain [Hz -1/2 ] LISA DECIGO Terrestrial detectors (e.g. LCGT) Confusion Noise moved above LISA band To be moved into TD band

17. Pre-conceptual design Differential FP interferometer Arm length: 1000 km Mirror diameter: 1 m Laser wavelength ： 0.532  m Finesse: 10 Laser power: 10 W Mirror mass: 100 kg S/C: drag free 3 interferometers Laser Photo- detector Arm cavity Drag-free S/C Arm cavity Mirror

18. Why FP cavity? Frequency Strain Radiation pressure noise f -2 Shot noise Shot noise f 1 Transponder type (e.g. LISA) Shot noise Shorten arm length Shot noise f 1 Radiation pressure noise f -2 Transponder type (e.g. LISA) Shorten arm length Implement FP cavity FP cavity type Better best- sensitivity

19. Drag free and FP cavity: compatible? Mirror S/C I S/C II

20. FP cavity and drag free : compatible? Local sensor Thruster Mirror Relative position between mirror and S/C S/C II S/C I

21. Drag free and FP cavity: compatible? Local sensor Thruster Mirror Relative position between mirror and S/C Actuator Interferometer output (GW signal) S/C II S/C I No signal mixture

22. Orbit and constellation (preliminary) Sun Earth Record disk Increase angular resolution Correlation for stochastic background

23. Inflation Formation of super- massive BH Verification of inflation Science by DECIGO Frequency [Hz] Correlation (3 years) Strain [Hz -1/2 ] 10 -3 10 -2 10 -1 1 10 10 2 10 3 10 -19 10 -20 10 -21 10 -22 10 -23 10 -24 10 -25 10 -26 (1000 M ◎ z=1) BH binary Coalescence 5 years NS binary (z=1) Coalescence 3 months Acceleration of Universe  Dark energy Radiation pressure noise Shot noise 1 unit Mini-black hole  Dark matter Brans Dicke parameter

24. Requirements  Force noise of DECIGO should be 50 times more stringent than LISA Acceleration noise in terms of h: comparable Distance: 1/5000 Mass: 100  Sensor noise of DECIGO should be10 times looser than LCGT Sensor noise in terms of h: comparable, Storage time: 10

25. Roadmap 2009 1011121314151617181920212223242526272829 Mission Objectives Test of key technologies Detection of GW w/ minimum spec. Test FP cavity between S/C Full GW astronomy Scope 1 S/C 1 arm 3 S/C 1 interferometer 3 S/C, 3 interferometer 3 or 4 units DICIGO Pathfinder (DPF) Pre-DECIGO DECIGO R&D Fabrication R&D Fabrication R&D Fabrication SWIM

26. DEDCIGO Pathfinder (DPF) Local Sensor Actuator Thruster Single satellite Earth orbit Altitude: 500km Sun synchronous Arm length: 1000 km Arm length: 30 cm

27. conceptual design and objectives of DPF Thruster Local Sensor Floating mirror Iodine cell Laser Actuator Test of drag- free system Test of locking system in space Test of laser in space Test of frequency stabilization system in space Observation of GW at 0.1 – 1 Hz

28. Payload and standard bus Stabilized. Laser source Interferometer module Satellite Bus system Solar Paddle Mission Thruster head On-board Computer Bus thruster Mast structure Satellite Bus (‘Standard bus’ system) DPF Payload Size : 950mm cube Weight : 150kg Power : 130W Data Rate: 800kbps Mission thruster x12 Power Supply SpW Comm. Size : 950x950x1100mm Weight : 200kg SAP : 960W Battery: 50AH Downlink : 2Mpbs DR: 1GByte 3N Thrusters x 4

29. Goal sensitivity of DPF

30. Detection range

31. R&D for Subsystems Frequency-stabilized laser ThrusterInterferometric sensor Drag-free model Electrostatic sensor/ actuator Test mass module

32. SWIM launch and operation Tiny GW detector module Launched in Jan. 23, 2009 Test mass Photo sensor Coil TAM: Torsion Antenna Module with free-falling test mass (Size : 80mm cube, Weight : ~500g) Reflective-type optical displacement sensor Separation to mass ~1mm Sensitivity ~ 10 -9 m/Hz 1/2 6 PSs to monitor mass motion ~47g Aluminum, Surface polished Small magnets for position control Photo ： JAXA In-orbit operation

33. Interim organization PI: Kawamura (NAOJ) Deputy: Ando (Tokyo) Executive Committee Kawamura (NAOJ), Ando (Tokyo), Seto (NAOJ), Nakamura (Kyoto), Tsubono (Tokyo), Tanaka (Kyoto), Funaki (ISAS), Numata (Maryland), Sato (Hosei), Kanda (Osaka city), Takashima (ISAS), Ioka (Kyoto) Pre-DECIGO Sato (Hosei) Satellite Funaki (ISAS) Science, Data Tanaka (Kyoto) Seto (NAOJ) Kanda (Osaka city) DECIGO pathfinder Leader: Ando (Tokyo) Deputy: Takashima (ISAS ) Detector Ueda (NAOJ) Housing Sato (Hosei) Laser Ueda (ILS) Musya (ILS) Drag free Moriwaki (Tokyo) Sakai (ISAS) Thruster Funaki (ISAS) Bus Takashima (ISAS) Data Kanda (Osaka city) Detector Numata (Maryland) Ando (Tokyo) Mission phase Design phase

34. Collaborations  LISA 1 st LISA-DECIGO workshop held in JAXA/ISAS (Nov. 2008)  Stanford Univ. Charge control using UV LED, etc. ⇒ MOU  NASA Goddard Fiber laser ⇒ started discussion  JAXA formation flight group Formation flight  Big bang center of the Univ. of Tokyo DECIGO adopted as one of the main themes  Advanced technology center of NAOJ Will make it a main nucleus of DPF  UNISEC (University Space Engineering Consortium) Started discussion

35. Funding Status  Proceeded to the final hearing as one of the two candidates for the 2 nd small science satellite run by JAXA/ISAS (launching three missions between 2012 and 2016), but not selected.  We will apply for the 3 rd mission. (The selection will take place in 2010.)

36. Conclusions  We need LCGT and DPF funded as soon as possible to establish the GW astronomy in the future!