The Japanese Space Gravitational Wave Antenna DECIGO

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The Japanese Space Gravitational Wave Antenna -
DECIGO

• Amaldi6 _at_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

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Contents

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

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

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Acceleration of Expansion of the Universe
DECIGO
Expansion Acceleration?
GW
NS-NS (z1)
Output
Template (No Acceleration)
Strain
Real Signal ?
Phase Delay1sec (10 years)
Time
Seto, Kawamura, Nakamura, PRL 87, 221103 (2001)
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DECIGO as a Future Gravitational Wave Detection
Project in Japan
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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

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Roadmap for DECIGO
06 07 08 09 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24
RD
Advanced RD
PF1
Design Fabrication
Observation
PF2
Design Fabrication
Observation
DECIGO
06 07 08 09 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24
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Pre-Conceptual Designfor 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)

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Fabry-Perot Type DECIGO
Around Lagrange Point
Fabry-Perot cavity
Drag-Free Satellite
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Actuating Force in FP-DECIGO
Anti-Gravity Anti-GW
Outer Satellite
The distance should be kept constant
Proof Mass
Anti-Drag Anti-Gravity Anti-GW
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Sensitivity of DECIGO
Force noise 1/100 of LISAs
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Preliminary Simulatorfor LISA-type DECIGO

• Built a preliminary simulator for DECIGO as a
  simulator for detecting the Earths gravity field
  around the Earth

Distance 50 km
Satellite 1
Satellite 2
vMAX 1 cm/s (Doppler Shift 20 kHz
??
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Schematic Diagram ofthe Preliminary Simulator
Monitor FB to DDS
Lock to mid-fringe by AOD
Simulate Doppler shift by AOD
Stabilized Frequency using 5 layer shielded
cavity (like LISA)
Simulate distance by optical fiber
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Sensitivity ofthe Preliminary Simulator
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Budget Situation for DECIGOand other GW Projects
in Japan

• Budget request for Frontier of All Wavelength
  Gravitational Wave Astronomy to be submitted
  this fall
• - TAMA and CLIO
• - RD for DECIGO
• - Pulsar Timing
• - Super-high frequency G.W. detection
• (Budget request for LCGT submitted this year from
  ICRR)

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RD for DECIGO
Overall Tests
Ground-based DECIGO Simulator (S. Kawamura, NAOJ)
DECIGO-Pathfinder (M. Ando, Univ. of Tokyo)

Key Technologies
Measurement System (K. Tsubono, Univ. of Tokyo)
Frequency Stabilization (T. Sato, Niigata Univ.)
Drag-free System (T. Ishikawa, JAXA-ISAS)
Evaluation of Light Source (M. Hosokawa, NICT)
Satellite Technologies (?, JAXA-ISAS)
Light Source (K. Ueda, ILS)
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Objectives of the RD

• RD of subsystems
• Overall tests by ground-based simulator and
  DECIGO-Pathfinder1
• RD for optional technologies
• Defining the objectives and conceptual design of
  DECIGO-PF2
• Establishing the conceptual design of DECIGO

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Ground-Based Simulater

• Test the system on earth as much as possible
• Investigate the system at low frequencies
• Observe GW at low frequencies

LF Pendulum
LF Pendulum
Laser
Seismic Isolation System
Seismic Isolation System
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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-ISASs new
  satellite plan

Measurement System
Laser
Resonated
Drag Free System
One Small Satellite
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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 RD
  this fall.
• We hope that we will be able to start the RD for
  DECIGO soon.