The Japanese Space Gravitational Wave Antenna DECIGO TAUP

The Japanese Space Gravitational Wave Antenna DECIGO TAUP 2007 @Sendai, Japan Aug 11, 2007 Seiji Kawamura, Masaki Ando, Takashi Nakamura, Kimio Tsubono, Takahiro Tanaka, Ikkoh Funaki, Naoki Seto, Kenji Numata, Shuichi Sato, Nobuyuki Kanda, Takeshi Takashima, Kunihito Ioka, Kazuhiro Agatsuma, Tomotada Akutsu, Tomomi Akutsu, Koh-suke Aoyanagi, Koji Arai, Yuta Arase, Akito Araya, Hideki Asada, Yoichi Aso, Takeshi Chiba, Toshikazu Ebisuzaki, Motohiro Enoki, Yoshiharu Eriguchi, Masa-Katsu Fujimoto, Ryuichi Fujita, Mitsuhiro Fukushima, Toshifumi Futamase, Katsuhiko Ganzu, Tomohiro Harada, Tatsuaki Hashimoto, Kazuhiro Hayama, Wataru Hikida, Yoshiaki Himemoto, Hisashi Hirabayashi, Takashi Hiramatsu, Feng-Lei Hong, Hideyuki Horisawa, Mizuhiko Hosokawa, Kiyotomo Ichiki, Takeshi Ikegami, Kaiki T. Inoue, Koji Ishidoshiro, Hideki Ishihara, Takehiko Ishikawa, Hideharu Ishizaki, Hiroyuki Ito, Yousuke Itoh, Shogo Kamagasako, Nobuki Kawashima, Fumiko Kawazoe, Hiroyuki Kirihara, Naoko Kishimoto, Kenta Kiuchi, Shiho Kobayashi, Kazunori Kohri, Hiroyuki Koizumi, Yasufumi Kojima, Keiko Kokeyama, Wataru　Kokuyama, Kei Kotake, Yoshihide Kozai, Hideaki Kudoh, Hiroo Kunimori, Hitoshi Kuninaka, Kazuaki Kuroda, Kei-ichi Maeda, Hideo Matsuhara, Yasushi Mino, Osamu Miyakawa, Shinji Miyoki, Mutsuko Y. Morimoto, Tomoko Morioka , Toshiyuki Morisawa, Shigenori Moriwaki, Shinji Mukohyama, Mitsuru Musha, Shigeo Nagano, Isao Naito, Noriyasu Nakagawa, Kouji Nakamura, Hiroyuki Nakano, Kenichi Nakao, Shinichi Nakasuka, Yoshinori Nakayama, Erina Nishida, Kazutaka Nishiyama, Atsushi Nishizawa, Yoshito Niwa, Masatake Ohashi, Naoko Ohishi, Masashi Ohkawa, Akira Okutomi, Kouji Onozato, Kenichi Oohara, Norichika Sago, Motoyuki Saijo, Masaaki Sakagami, Shin-ichiro Sakai, Shihori Sakata, Misao Sasaki, Takashi Sato, Masaru Shibata, Hisaaki Shinkai, Kentaro Somiya, Hajime Sotani, Naoshi Sugiyama, Yudai Suwa, Hideyuki Tagoshi, Kakeru Takahashi, Keitaro Takahashi, Tadayuki Takahashi, Hirotaka Takahashi, Ryuichi Takahashi, Ryutaro Takahashi, Takamori Akiteru, Tadashi Takano, Keisuke Taniguchi, Atsushi Taruya, Hiroyuki Tashiro, Mitsuru Tokuda, Masao Tokunari, Morio Toyoshima, Shinji Tsujikawa, Yoshiki Tsunesada, Ken-ichi Ueda, Masayoshi Utashima, Hiroshi Yamakawa, Kazuhiro Yamamoto, Toshitaka Yamazaki, Jun'ichi Yokoyama, Chul-Moon Yoo, Shijun Yoshida, Taizoh Yoshino

What is DECIGO? Deci-hertz Interferometer Gravitational Wave Observatory (Kawamura, et al. , CQG 23 (2006) S 125 -S 131) l Bridges the gap between LISA and terrestrial detectors l Low confusion noise Extremely high sensitivity Strain [Hz-1/2] 10 -18 10 -20 Ab have ov e L mov ISA ed ba LISA nd 10 -22 Confusion wil int l m o T ov Db e an d Terrestrial detectors (e. g. LCGT) DECIGO Noise 10 -24 10 -2 100 102 Frequency [Hz] 104

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 Photodetector Drag-free S/C Arm cavity Mirror

Implement FP cavity f 1 e is no Shorten arm length ot Shot noise Transponder type (e. g. LISA) Sh re su res Shot noise ot no is e f 1 np tio dia -2 Ra se f i no re su res np tio dia -2 Ra se f i no Strain Shorten arm length Sh Transponder type (e. g. LISA) Why FP cavity? Implement FP cavity type Frequency Better bestsensitivity

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

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

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

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

Goal Sensitivity and Science 10 -19 10 -24 Verification of inflation 10 -26 10 -3 Inflation 10 -2 ary z= 1) Coalescence 5 years 1 unit 3 months ise no 10 -23 10 -25 M bin ◎ re su 10 -22 00 res np tio Strain [Hz-1/2] dia Ra Formation of 10 -20 Supermassive BH 10 -21 BH (10 NS bin Acceleration of Universe Shot noise (z= 1) ⇓ Correlation Dark energy (3 years) Coalescence 10 -1 ary 1 10 Frequency [Hz] 102 103

Requirements l Acceleration noise should be suppressed below radiation pressure noise – Force noise: DECIGO = LISA/50 (Acceleration noise in terms of h: 1, Distance: 1/5000, Mass: 100) – Fluctuation of magnetic field, electric field, gravitational field, temperature, pressure, etc. l Sensor noise should be suppressed below shot noise. – Phase noise: DECIGO = LCGT× 10 (Sensor noise in terms of h: 1, storage time: 10) – Frequency noise, intensity noise, beam jitter, etc. l Thruster system should satisfy range, noise, bandwidth, and durability.

Roadmap 2007 08 09 10 11 12 13 Mission R&D Fabrication 14 15 16 17 18 19 R&D Fabrication DICIGO Pathfinder (DPF) Ando’ s talk 20 21 22 23 24 25 26 R&D Fabrication Pre-DECIGO Objectives Scope Test of key technologies Detection of GW w/ minimum spec. Test FP cavity between S/C Full GW astronomy 1 S/C 1 arm 3 S/C 1 interferometer 3 S/C, 3 interferometer 3 or 4 units

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 (Merryland), Sato (NAOJ), Kanda (Osaka city), Takashima (ISAS), Ioka (Kyoto) Pre-DECIGO Sato (NAOJ) Detector Science, Data Numata (Merryland) Ando (Tokyo) Tanaka (Kyoto) Seto (NAOJ) Kanda (Osaka city) Satellite Funaki (ISAS) Design phase DECIGO pathfinder Leader: Ando (Tokyo) Deputy: Takashima (ISAS) Mission phase Detector Laser Housing Drag free Thruster Bus Data Ando (Tokyo) Ueda (ILS) Musya (ILS) Sato (NAOJ) Moriwaki (Tokyo) Sakai (ISAS) Funaki (ISAS) Takashima (ISAS) Kanda (Osaka city)

Current status • There are now 140 members from 50 institutes in DECIGO working group • Budget request (DECIGO R&D and fabrication of DPF, $20 M, 6 years) was rejected. • We will submit budget request (R&D for DECIGO and DP, $10 M, 5 -6 years) this year again. • DPF working group was formally approved by JAXA/ISAS. • Budget request (R&D for DPF, $65 K, 1 year) to JAXA/ISAS was approved.

Summary l l DECIGO can not only bridge the gap between terrestrial detectors and LISA, but also open a very deep window at 0. 1 – 10 Hz. DECIGO will use FP arm cavity to further improve the sensitivity. We have obtained some budget to initiate R&D for DPF. We hope that we will obtain a bigger budget for DECIGO R&D, and that DPF mission will be approved soon!

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

Ground-based simulator (juggling interferometer) l l Position ~2 m Continually Freely falling Moving up and down l Realize continual free-fall condition Measure force noise Test clamp release system High GW sensitivity at 0. 1 – 10 Hz Might be applied to future terrestrial detectors Clamp ~ 1 sec Hold Release Time

Fortune Cookie

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 2002 1 st DECIGO workshop 2003 2 nd DECIGO workshop (FP-type DECIGO suggested by Ando) 2005 3 rd DECIGO workshop 2006 4 th DECIGO workshop (FP-type DECIGO adopted as a pre-conceptual design) 2007 5 th DECIGO workshop