1. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) DECIGO Pathfinder Masaki Ando (Department of Physics, The University of Tokyo) (Department of Physics, The University of Tokyo) and DECIGO Pathfinder working Group and DECIGO Pathfinder working Group

2. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 2 Introduction (1) DECIGO roadmap LISA LPF Ad. LIGO LCGT

3. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 3 DECIGO-PF (1) DECIGO Pathfinder (DPF) DECIGO-PF One small satellite (Weight: ~200-300kg, Orbit: around the earth) 10cm Fabry-Perot cavity formed by free masses Stabilized laser source Drag-free control system Local Sensor Actuator Thruster Gravitational-wave observation (5) Observation for low-frequency (0.1-1Hz) GWs Mid.-scale BHs at the Galactic center Test and demonstration for DECIGO (1) Drag-free control system (2) Laser source and its stabilization system (3) Control of Fabry-Perot interferometer (4) Launch-lock system

4. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 4 DECIGO-PF (2) DPF diagram Fabry-Perot interferometer Finesse : 100 Length : 10cm Test mass : 1kg Signal extraction by PDH Laser source Nd:YAG laser (1064nm) Power : 25mW Freq. stab. by reference cavity Drag-free control Local sensor signal  Feedback to thrusters/wheels Mission weight : ~100kg Mission space : ~90 x 90 x 90 cm

5. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 5 DECIGO-PF (3) DPF sensitivity Satellite mass : 100kg, Area: 1m 2 Altitude: 750km Thruster noise: 0.1μN/Hz 1/2 Laser source : 1064nm, 25mW IFO length : 10cm Finesse : 100, Mirror mass : 1kg Q-factor : 10 5, Substrate: Fused Silica Temperature : 293K (Preliminary parameters)

6. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 6 DECIGO-PF (4) DPF orbit DPF Selection of DPF orbit Launch chance (Cost, Launch window) Operation (Power supply, Telemetry) Stability, Noises Low-earth orbit Altitude 750km Polar sun synchronous orbit 750km No eclipse  Full-time operation Higher altitude will be desirable to reduce the effect of the earth (Earth’s gravity, terrestrial magnetism, residual atmosphere) Depends on launch chance Earth Sun

7. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 7 DECIGO-PF (5) Gravity-gradient noise Global gravity field model Public data obtained by GRACE Up to 150th-order in spherical harmonics Satellite velocity of 5km/sec  Estimate the noise spectrum Assume 2% vertical-horizontal coupling Cut-off at 0.03Hz: originates in the model resolution  Unknown at higher frequency This will not be a problem: higher-order contribution will be negligible order of ~(Re/r) n Observe gravity field with higher resolution?

8. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 8 DECIGO-PF (6) Geomagnetic noise Fluctuation in geomagnetic field Public data at Esashi observatory 1 sample/min data  Extrapolate for higher frequency Two effect by geomagnetic field: Satellite motion in magnetic field Fluctuation in geomagnetic field Geomagnetic field model IGRF-10 model (10 th generation of International Geomagnetic Reference Field) Altitude 750km Satellite velocity of 5km/sec Satellite self-field Effect of geomagnetic field: smaller than satellite self-field ~10 -7 T  noise level ~ 1.5 x 10 -16 m/s 2 /Hz 1/2 Magnetic-field noise

9. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 9 DECIGO-PF (7) Survey of noise sources Residual Gas Thermal radiation Magnetic field Laser freq. noise Force Acceleration Acceleration noiseDisplacement noise

10. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 10 DECIGO-PF (8) Comparison with other detectors LCGT DECIGO Galactic binary Foreground noise Core-collapse super nova NS inspiral Inspiral of Massive BH Galactic binary ScoX-1 (1yr) Pulsar (1yr) LISA Gravity-gradient noise for terrestrial detectors DPF limit Only a little observation data at low-frequency band Doppler tracking: h ~10 -15 (10 -4 -10 -2 Hz) Pulsar timing: h ~10 -14 (10 -8 Hz) GWs from Early universe (  gw =10 -14 )

11. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 11 DECIGO-PF (9) DPF targets Quasi-nomal mode oscillation of massive BH Binary inspiral of mid.-scale BHs Events at Galactic center will be detectable with SNR~5 h ~ 10 -15, f ~ 0.3 Hz Distance 1Mpc, m = 10 5 M sun h ~ 10 -15, f ~ 4 Hz Distance 10kpc, m = 10 3 M sun

12. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 12 DPF status (1) Brief history 2004 December Call for suggestions of small satellite mission by JAXA 2005 January Submit a proposal of small GW detector mission ~30 missions were submitted 2006 October Call for proposals of small satellite mission by JAXA 2006 November Submit a proposal of GW-detector satellite as DECIGO pathfinder (DPF) 16 missions were accepted as working groups (10 science, 6 engineering missions), including DPF 2007 April Review meeting for these missions 2007 August DPF has been selected as one of 5 Pre-Phase-A missions R&D costs have been funded

13. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 13 DPF status (2) DPF status JAXA is planning to launch 3 small satellite by the year 2013 using next-generation solid rocket booster under development Reduce time and cost by means of ‘Standard bus system’ Preliminary parameters Bus weight : ~ 200kg, Bus power : ~ 900W Downlink ~ 4Mbps, Data storage ~ 1GByte 3-axes angular control 1 st mission (2011) has been decided to be TOPS (Space telescope mission for planet observation) 2 nd and 3 rd mission will be selected by 2009 March Candidate missions DPF: GW observation DIOS: X-ray telescope for dark baryon investigation ERG: Plasma and particle detector for geo-space investigation Satellite for Magnet-plasma sail technology demonstration

14. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 14 DPF status (3) R&D plan for DPF Laser frequency stabilization Mirror and its housing (local sensor, actuator, launch-lock system) Micro thruster Drag-free control simulation Detailed design and noise investigation (Under discussion) Required to submit Phase-A proposal by 2009 March R&D for core technologies Target: launch in 2012 or 2013 as 2 nd or 3 rd standard small satellite of JAXA

15. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 15 Summary One small satellite (Weight: ~200-300kg, Orbit: around the earth) 10cm Fabry-Perot cavity formed by free masses Stabilized laser source Drag-free control system Local Sensor Actuator Thruster Gravitational-wave observation Test and demonstration for DECIGO DECIGO pathfinder: First demonstration satellite for DECIGO Selected and funded as one of the candidates of JAXA’s small satellite missions Hoping to be launched in 2012 - 2013 0.1Hz-1Hz band BH QNM and Mid.-BH inspiral at Galactic center

16. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 16 Topics Steps for DPF Small module to be launched in 2008 SDS-I : Small (~100kg) satellite for demonstration of space technologies To be launched in 2008 summer by H-IIA as piggy-back satellite of GOSAT SWIM  : very small GW detector module will be included in SWIM (SpaceWire Interface demonstration Module) Small test-mass module Test mass Photo sensor Coil- magnet actuator Free-falling experiment using balloon BOV 2.5 : Free-falling vehicle from large balloon ~30 sec free-falling streach from 40km altitude Drag-free control system using gas-jet thrusters Prototype of SWIM  is included in BOV Experiment module Diameter ~ 28cm

17. International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 17 End End