Sora Japan Feb. 5, 2009 Seiji Kawamura, Masaki Ando, Takashi Nakamura, Kimio Tsubono, Naoki Seto, Shuichi Sato, Kenji Numata, Nobuyuki Kanda, Ikkoh Funaki, Takeshi Takashima, Takahiro Tanaka, Kunihito Ioka, Kazuhiro Agatsuma, Koh-suke Aoyanagi, Koji Arai, Akito Araya, Hideki Asada, Yoichi Aso, Takeshi Chiba, Toshikazu Ebisuzaki, Yumiko Ejiri, 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, Nobuki Kawashima, Fumiko Kawazoe, 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, Kouji Nakamura, Hiroyuki Nakano, Kenichi Nakao, Shinichi Nakasuka, Yoshinori Nakayama, Kazuhiro Nakazawa, Erina Nishida, Kazutaka Nishiyama, Atsushi Nishizawa, Yoshito Niwa, Yoshiyuki Obuchi, Masatake Ohashi, Naoko Ohishi, Masashi Ohkawa, Norio Okada, 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, Rieko Suzuki, Hideyuki Tagoshi, Fuminobu Takahashi, Kakeru Takahashi, Keitaro Takahashi, Ryutaro Takahashi, Ryuichi Takahashi, Tadayuki Takahashi, Hirotaka Takahashi, Takamori Akiteru, Tadashi Takano, Keisuke Taniguchi, Atsushi Taruya, Hiroyuki Tashiro, Mitsuru Tokuda, Yasuo Torii, Morio Toyoshima, Shinji Tsujikawa, Yoshiki Tsunesada, Akitoshi Ueda, Ken-ichi Ueda, Masayoshi Utashima, Yaka Wakabayashi, Hiroshi Yamakawa, Kazuhiro Yamamoto, Toshitaka Yamazaki, Jun'ichi Yokoyama, Chul-Moon Yoo, Shijun Yoshida, Taizoh Yoshino

Outline  Gravitational wave  DECIGO  DECIGO pathfinder  Summary

Distortion of space ~ Not yet detected! Predicted by Einstein Emitted from accelerating objects Propagates as tidal distortion of space Gravitational wave

GW Sources Neutron star / black hole binaries Supernova Beginning of the universe Etc.

380,000 year (Transparent to radiation) EM 1 sec (Formation of Proton, Neutron) Neutrino How far (old) can we see? Beginning of the universe 13.7 billion year (Now) GW sec (Planck time ）

Detection of GW by laser interferometer Laser Interfering beam Beam splitter Suspended Mirror Detector

The longer arm length gives larger signals! Laser Photodetector Mirror Laser Photodetector Mirror

Large-scale detectors LIGO (4 km) VIRGO (3 km) GEO (600 m) TAMA (300 m) CLIO (100 m)

Space antenna Much longer arm length

LISA Arm length: 5,000,000km Frequency range: 1 mHz Hz Target Source: White dwarf binary, Giant BH coalescence Optical configuration: Light transponder LISA project

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 Frequency [Hz] Strain [Hz -1/2 ] LISA DECIGO Terrestrial detectors (e.g. LCGT) Confusion Noise

Pre-conceptual design Differential FP interferometer Arm length: 1000 km Mirror diameter: 1 m Laser wavelength ：  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

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

Local sensor Thruster Mirror Relative position between mirror and S/C S/C II S/C I 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

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

Science by DECIGO Inflation (  GW =2  ) Formation of Super- massive BH Verification of inflation Frequency [Hz] Correlation (3 years) Strain [Hz -1/2 ] (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 cluster

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, (2001)

Science by DECIGO Inflation (  GW =2  ) Formation of Super- massive BH Verification of inflation Frequency [Hz] Correlation (3 years) Strain [Hz -1/2 ] (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 cluster

Roadmap Mission Objectives Test of key technologies Observation run of GW 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

DECIGO Pathfinder (DPF) Laser PD Floating Mirrors Drag-free S/C DECIGO DPF 30 cm 1,000 km Shrink the arm length from 1,000 km to 30 cm

Small Science Satellite Series ISAS/JAXA plan to launch 3 missions in 5 years starting from 2011 DPF was selected as one of important mission candidates; a budget for R&D was allocated DPF aims at being selected as 2 nd or 3 rd mission (1 st mission already selected)

Summary GW is a powerful means to explore the universe. DECIGO can detect GWs from the beginning of the universe and provide other important science results. DPF was selected as on of the important mission candidates for small science satellite series.

Let DPF fly!