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The Japanese Space Gravitational Wave Antenna - DECIGO: 

The Japanese Space Gravitational Wave Antenna - DECIGO Amaldi6 @Okinawa June 22, 2005 Seiji Kawamura, Takashi Nakamura, Masaki Ando, Kimio Tsubono, Naoki Seto, Shigeo Nagano, Takahiro Tanaka, Takehiko Ishikawa, Ken-ichi Ueda, Mitsuru Musha, Takashi Sato, Mizuhiko Hosokawa, Kenji Numata, Hisashi Hirabayashi, Tadashi Takano, Masa-Katsu Fujimoto, Atsushi Taruya, Yoshiaki Himemoto, Chul-Moon Yoo, Kenichi Nakao, Tomohiro Harada, Kunihito Ioka, Norichika Sago, Wataru Hikida, Shuichi Sato, Keiko Kokeyama, Mitsuhiro Fukushima, Hiroo Kunimori, Toshitaka Yamazaki, Masashi Ohkawa, Tatsuaki Hashimoto, Koh-suke Aoyanagi, Kazuhiro Agatsuma, Tomotada Akutsu, Hideki Asada, Yoichi Aso, Koji Arai, Akito Araya, Takeshi Ikegami, Koji Ishidoshiro, Kiyotomo Ichiki, Yousuke Itoh, Kaiki T. Inoue, Yoshiharu Eriguchi, Naoko Ohishi, Masatake Ohashi, Kenichi Oohara, Akira Okutomi, Shogo Kamagasako, Nobuki Kawashima, Mari Kawamura, Nobuyuki Kanda, Katsuhiko Ganzu, Kenta Kiuchi, Hideaki Kudoh, Kazuaki Kuroda, Kazunori Kohri, Yoshihide Kozai, Yasufumi Kojima, Shiho Kobayashi, Motoyuki Saijo, Masaaki Sakagami, Shihori Sakata, Misao Sasaki, Masaru Shibata, Hisaaki Shinkai, Naoshi Sugiyama, Hajime Sotani, Hirotaka Takahashi, Ryuichi Takahashi, Ryutaro Takahashi, Hideyuki Tagoshi, Hiroyuki Tashiro, Keisuke Taniguchi, Takeshi Chiba, Shinji Tsujikawa, Yoshiki Tsunesada, Masao Tokunari, Isao Naito, Hiroyuki Nakano, Kouji Nakamura, Atsushi Nishizawa, Yoshito Niwa, Choetsu Nozawa, Kazuhiro Hayama, Takashi Hiramatsu, Toshifumi Futamase, Kei-ichi Maeda, Hideo Matsuhara, Hiromi Mizusawa, Yasushi Mino, Osamu Miyakawa, Shinji Miyoki, Shinji Mukohyama, Toshiyuki Morisawa, Kazuhiro Yamamoto, Jun'ichi Yokoyama, Shijun Yoshida, and Taizoh Yoshino

Contents: 

Contents What is DECIGO? Current Status Budget Situation Preliminary Experiment Summary

Gap between TerrestrialDetectors and LISA: 

Gap between Terrestrial Detectors and LISA 10-4 104 102 100 10-2 Frequency [Hz] Strain [Hz-1/2] LISA Terrestrial Detectors (e.g. LCGT) Gap

DECIGO Bridges the Gap: 

DECIGO Bridges the Gap 10-4 104 102 100 10-2 Frequency [Hz] Strain [Hz-1/2] LISA DECIGO Terrestrial Detectors (e.g. LCGT) The Japanese Space Gravitational Wave Antenna - DECIGO Deci-hertz Interferometer Gravitational Wave Observatory 　

Importance of Bridgingthe Gap: 

Importance of Bridging the Gap New window brings new science! Observe inspiral sources that have moved above the LISA band Observe inspiral sources that have not yet moved into the ground-based detector band Especially inspiral of IMBH Completely new sources could be detected Completely new science could be obtained

Acceleration of Expansion of the Universe: 

Acceleration of Expansion of the Universe NS-NS (z～1) GW DECIGO Output Expansion ＋Acceleration? Time Strain Template (No Acceleration) Real Signal ? Phase Delay～1sec (10 years) Seto, Kawamura, Nakamura, PRL 87, 221103 (2001)

DECIGO as a Future Gravitational Wave Detection Project in Japan: 

DECIGO as a Future Gravitational Wave Detection Project in Japan

History of DECIGO: 

History of DECIGO 1999 the LISA study group convened by Tsubono 2000 Short-arm space antenna suggested by Kawamura 2001 Space GW antenna WG convened as one of the possible future projects in NAOJ 2001 Named as DECIGO in the PRL paper by Seto, Kawamura, Nakamura (DECIDE and GO) 2002 1st DECIGO-WG meeting 2003 2nd DECIGO-WG meeting (FP-type DECIGO suggested by Ando) 2005 3rd DECIGO-WG meeting

Roadmap for DECIGO: 

Roadmap for DECIGO 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Design & Fabrication Observation R&D Advanced R&D PF1 DECIGO Design & Fabrication Observation PF2

Pre-Conceptual Designfor DECIGO: 

Pre-Conceptual Design for DECIGO LISA-type DECIGO - Shorter arm length Fabry-Perot-Cavity-type DECIGO - Even shorter arm length - Resonance of light in the cavity For both types - Better shot noise (higher power, shorter wavelength, larger mirror) - Better force noise (heavier mass)

Fabry-Perot Type DECIGO: 

Fabry-Perot Type DECIGO Drag-Free Satellite Around Lagrange Point Fabry-Perot cavity

Actuating Force in FP-DECIGO: 

Actuating Force in FP-DECIGO Anti-Drag + Anti-Gravity +Anti-GW Anti-Gravity +Anti-GW Proof Mass Outer Satellite The distance should be kept constant

Sensitivity of DECIGO: 

Sensitivity of DECIGO Force noise= 1/100 of LISA’s

Preliminary Simulatorfor LISA-type DECIGO: 

Preliminary Simulator for LISA-type DECIGO Built a preliminary simulator for DECIGO as a simulator for detecting the Earth’s gravity field around the Earth 地球 Distance: 50 km vMAX: 1 cm/s （Doppler Shift: 20 kHz Satellite 2 Satellite 1

Schematic Diagram ofthe Preliminary Simulator: 

Schematic Diagram of the Preliminary Simulator Simulate Doppler shift by AOD Simulate distance by optical fiber Lock to mid-fringe by AOD Monitor FB to DDS Stabilized Frequency using 5 layer shielded cavity (like LISA)

Sensitivity ofthe Preliminary Simulator: 

Sensitivity of the Preliminary Simulator

Budget Situation for DECIGOand other GW Projects in Japan: 

Budget Situation for DECIGO and other GW Projects in Japan Budget request for “Frontier of All Wavelength Gravitational Wave Astronomy” to be submitted this fall - TAMA and CLIO - R&D for DECIGO - Pulsar Timing - Super-high frequency G.W. detection (Budget request for LCGT submitted this year from ICRR)

R&D for DECIGO: 

R&D for DECIGO Overall Tests Key Technologies Ground-based DECIGO Simulator (S. Kawamura, NAOJ) DECIGO-Pathfinder (M. Ando, Univ. of Tokyo) Measurement System (K. Tsubono, Univ. of Tokyo) Drag-free System (T. Ishikawa, JAXA-ISAS) Light Source (K. Ueda, ILS) Frequency Stabilization (T. Sato, Niigata Univ.) Evaluation of Light Source (M. Hosokawa, NICT) Satellite Technologies (?, JAXA-ISAS)

Objectives of the R&D: 

Objectives of the R&D R&D of subsystems Overall tests by ground-based simulator and DECIGO-Pathfinder1 R&D for optional technologies Defining the objectives and conceptual design of DECIGO-PF2 Establishing the conceptual design of DECIGO

Ground-Based Simulater: 

Ground-Based Simulater Laser LF Pendulum Seismic Isolation System Seismic Isolation System Test the system on earth as much as possible Investigate the system at low frequencies Observe GW at low frequencies LF Pendulum

Pathfinder: 

Pathfinder Test the system which can be tested only in space (Drag-free system) Check if the measurement system works in space Observe GW at low frequencies This effort couples with the JAXA-ISAS’s new satellite plan Laser Drag Free System Measurement System One Small Satellite Resonated

Summary: 

Summary It is important to bridge the gap between terrestrial detectors and LISA. The Japanese space antenna DECIGO can bridge the gap. We have started serious investigation of DECIGO. We will submit a budget request for DECOGO R&D this fall. We hope that we will be able to start the R&D for DECIGO soon.