decigo : the japanese space gravitational wave antenna

11th Marcel Grossmann Meeting on General Relativity (July 23 - 29, 2006, Freie Universität Berlin)

DECIGO :DECIGO : the Japanese Space Gravitational Wave the Japanese Space Gravitational Wave AntennaAntenna

Seiji Kawamura, Takashi Nakamura, Masaki Ando, Kimio Tsubono, Naoki Seto, Kenji Numata, Takahiro Tanaka, Kazuhiro Agatsuma, Tomotada Akutsu, Koh-suke Aoyanagi, Koji Arai, Akito Araya, Hideki Asada, Yoichi Aso, Takeshi Chiba, Toshikazu Ebisuzaki, Motohiro Enoki, Yoshiharu Eriguchi, Masa-Katsu Fujimoto, Mitsuhiro Fukushima, Toshifumi Futamase, Katsuhiko Ganzu, Tomohiro Harada, Tomohiro Harada, Tatsuaki Hashimoto, Kazuhiro Hayama, Wataru Hikida, Yoshiaki Himemoto, Hisashi Hirabayashi, Takashi Hiramatsu, Mizuhiko Hosokawa, Kiyotomo Ichiki, Takeshi Ikegami, Kaiki T. Inoue, Kunihito Ioka, Koji Ishidoshiro, Takehiko Ishikawa, Hiroyuki Ito, Yousuke Itoh, Shogo Kamagasako, Nobuyuki Kanda, Nobuki Kawashima, Hiroyuki Kirihara, Kenta Kiuchi, Werner Klaus, Shiho Kobayashi, Kazunori Kohri, Yasufumi Kojima, Keiko Kokeyama, Yoshihide Kozai, Hideaki Kudoh, Hiroo Kunimori, Kazuaki Kuroda, Kei-ichi Maeda, Hideo Matsuhara, Yasushi Mino, Jun-ichi Miura, 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, Erina Nishida, Atsushi Nishizawa, Yoshito Niwa, Masatake Ohashi, Naoko Ohishi, Masashi Ohkawa, Akira Okutomi, Kenichi Oohara, Norichika Sago, Motoyuki Saijo, Masaaki Sakagami, Shin-ichiro Sakai, Shihori Sakata, Misao Sasaki, Shuichi Sato, Takashi Sato, Masaru Shibata, Hisaaki Shinkai, Kentaro Somiya, Hajime Sotani, Naoshi Sugiyama, Hideyuki Tagoshi, Tadayuki Takahashi, Ryutaro Takahashi, Ryuichi Takahashi, Hirotaka Takahashi, Takamori Akiteru, Tadashi Takano, Keisuke Taniguchi, Atsushi Taruya, Hiroyuki Tashiro, Masao Tokunari, Morio Toyoshima, Shinji Tsujikawa, Yoshiki Tsunesada, Ken-ichi Ueda, Kazuhiro Yamamoto, Toshitaka Yamazaki, Jun'ichi Yokoyama, Chul-Moon Yoo, Shijun Yoshida, Taizoh Yoshino

Illustration/ KAGAYA

Masaki AndoMasaki Ando(Department of Physics,

the University of Tokyo)


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ContentsContents

　　　　 Introduction

　　　　 Pre-conceptual Design

　　　　 Science

　　　　 Roadmap and R&D

　　　　 Summary


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Gravity Gradient noise (Terrestrial Detectors)

Confusion noise by Galactic binaries

10–4 10–2 100 102 104

10–26

10–24

10–22

10–20

10–18

10–16

Frequency [Hz]

Str

ain

[1

/Hz1

/2]

IntroductionIntroduction

DECIGO 　Deci-hertz Interferometer Gravitational Wave Observatorybridges the gap between LISA and terrestrial detectors

LCGT, Ad-LIGO

Primordial Background GW (gw=10-14)

MBH Coalescence

Resolved Galactic binary

LISA

LIGO

Stellar-core Collapse

NS-NS binary Inspiral

ScoX-1 (1yr)

Pulsar　　 (1yr)

DECIGO


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Pre-conceptual Design (1)Pre-conceptual Design (1)

Pre-conceptual Design 　FP-Michelson interferometer

Arm length: 1000 km Finesse: 10

Laser Power: 10 W Wavelength: 532 nm

Mirror (Test mass) Diameter: 1 m Mass: 100 kg Shielded by S/C

Orbit and constellation: TBD

Laser

Drag-free satellite

Arm cavity

Arm cavity

Drag-free satellite Drag-free satellite

PD

PD

S. Kawamura, et al., CQG 23 (2006) S125-S131


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SensitivityFloor level : 2x10-24 /Hz1/2 (0.1 - 10Hz)

10–4 10–3 10–2 10–1 100 101 102 10310–25

10–24

10–23

10–22

10–21

10–20

10–19

10–18

Frequency [Hz]

Str

ain

[

1/H

z1/2]

LCGT

LISA

DECIGO(FP type, 1000km)

Laser: 10W, 532nmMass: 100kgMirror: 1m dia.

Noise sources Low freq.: Acceleration noise, Radiation pressure noise High freq.: Shot noise (7.5Hz cut-off freq. )


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Interferometer DesignTransponder type vs Direct-reflection type Compare: Sensitivity curve and Expected Science Same detector parameters (Mirror, Laser, etc.)

10–4 10–3 10–2 10–1 100 101 102 10310–25

10–24

10–23

10–22

10–21

10–20

10–19

10–18

Frequency [Hz]

Str

ain

[

1/H

z1/2]

LCGT

LISA

DECIGO(LISA type, 5x104km)

DECIGO(FP type, 1000km)

Laser: 10W, 532nmMass: 100kgMirror: 1m dia.

WD-W

D

confusion

noise

Decisive factor: Binary confusion noise


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Arm lengthCavity arm length : Limited by diffraction loss

Calculate Effective reflectivity (TEM00 TEM00)

Laser wavelength : 532nm, Mirror diameter: 1m Optimal beam size

101 102 103 104 105 106 107 108 109 101010–4

10–3

10–2

10–1

100

Arm Length [m]

Ra

tio

of

av

aila

ble

po

we

r

LISALCGTTAMA DECIGO Dif

fra

cti

on

Lo

ss

(5x109m)(3x103m)(300 m)

Mirror diameter : 1mOptimal beam profile

(1x106m)

Nd:YAG laser : 532nm


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Requirements

Practical force noise: 4x10-17 N/Hz1/2 per mirror (Mirror mass: 100kg)

Frequency Noise (at 1 Hz) First-stage stabilization ： 1 Hz/Hz1/2

Stabilization gain by common-mode arm length ： 105

Common-mode rejection ratio ： 105


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Cavity and S/C control

Local Sensor

Actuator

Displacement signal between the two Mirrors

Thruster Thruster

Displacement Signal between S/C and Mirror

Mirror

S/C 1 S/C 2

Fig: S. Kawamura

Cavity length change PDH error signal Mirror position (and Laser frequency)Relative motion between mirror and S/C Local sensor S/C thruster


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S/C thruster force

0 12 24 36 48 60–40

–30

–20

–10

0

10

20

30

40

Le

ng

th C

ha

ng

e [

km

]

Time [month]

S/C orbit : TBD

(ex) Similar orbit as that of LISA Numerical simulation of multi-bode system Include gravity of planets Arm length: 1000km　　　 Earth-like orbit, 20deg. Behind the earth

Length control is indispensableAcceleration to be controlled: ~4x10-12 m/s2

0 5 10 15 20 25 30–15

–10

–5

0

5

10

15

Le

ng

th C

ha

ng

e [

m]

Time [day]

Black curve: parabolic fitting


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Science by DECIGO (1)Science by DECIGO (1)

NS+NS@z=1

BH+BH(1000Msun)

@z=1

Correlationfor 3 years

NS-NS (1.4+1.4Msun) z<1 (SN>26: 7200/yr) z<3 (SN>12: 32000/yr) z<5 (SN>9: 47000/yr)IMBH (1000+1000Msun) z<1 (SN>6000)

Binary Inspiral

Fig: N. Seto

Extremely high rate for NS-NS inspirals


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NS-NS (z ～1)

GW

DECIGO

Output

Expansion ＋Acceleration?

Time

Str

ai

n

Template (No Acceleration)

Real Signal ? Phase Delay ～ 1sec (10

years)Seto, Kawamura, Nakamura, PRL 87, 221103 (2001)

Acceleration of Expansion of the Universe


Distant binary is a precise clock Monitor Doppler shift


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Distance – Red shift relationship for NS-NS binaries Constraint to dark energy

Distance: determined directly by GW observation

Red shift: determined by identifying the host galaxies (10 arcsec at z=1 for two far-separate DECIGOs)

Constraint to Dark Energy



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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

Roadmap to DECIGO

Roadmap and R&D (1)Roadmap and R&D (1)


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Local Sensor

ActuatorThruster

Single S/C with Test mass Laser interferometer Drag-free system

Objectives Drag-free system Cavity locking in space Modest sensitivity at 0.1 – 1

Hz GW observation

Details: TBD

DECIGO Pathfinder1


Fig: S. Kawamura


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Laser

Drag-free satellite

Arm cavity

Arm cavity

Drag-free satellite

Drag-free satellite

PD

PD

DECIGO with modest specification

Objectives Cavity locking between two S/C Meaningful sensitivity GW observation

Details: TBD

DECIGO Pathfinder2


Fig: S. Kawamura


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Clamp

TimeV

ert

ical

Posit

ion2

m

1 sec

Release Hold

Release Hold

Release Hold

Objectives

Continual free-fall environment

Clamp release

Modest sensitivity down to 0.1Hz

Possibility of long arm

DECIGO Simulator


Fig: S. Kawamura


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Satellite A

Satellite B

Thruster Thruster

Actuator

Air-hockey table

Mirror A

Mirror B

Local sensor

Local sensor

Objectives

Lock acquisition

Drag-free control demonstration

DECIGO Demonstrator


Fig: S. Kawamura


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Budget request for “Frontier of All Wavelength Gravitational Wave Astronomy” submitted in 2005

- TAMA and CLIO- R&D for DECIGO- Pulsar Timing- Super-high frequency G.W. detection

Not approved to our surpriseTry again?

Budget



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DECIGO will have an extremely good sensitivity

and open the GW window widely.

DECIGO requires

extremely challenging technology development.

We hope that we will be able to

start the R&D for DECIGO very soon.

SummarySummary


EndEnd

decigo : the japanese space gravitational wave antenna

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