Sora

HEPL SeminarFeb. 11, 2009 @ Stanford

Univ.Seiji Kawamura

(National Astronomical Observatory of Japan)

OutlineGravitational waveDECIGODECIGO pathfinderSummaryAppendix

– Displacement noise free interferometer– Juggling interferometer

Distortion of space ~ 10-23

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)

EM1 sec(Formation of

Proton, Neutron)

Neutrino

How far (old) can we see?

Beginning ofthe universe

13.7 billion year(Now)

GW10 -43 sec(Planck time）

Gravitational wave astronomy

Detection of GWby laser interferometer

Laser

Interfering beam

Beam splitter

Suspended Mirror Suspended Mirror

Detector

The longer arm length gives larger signals!

Laser

Photodetector

Mirror

Mirror

Laser

Photodetector

Mirror

Mirror

Large-scale detectors

LIGO (4 km)

LIGO (4 km)

VIRGO (3 km)

GEO (600 m)

TAMA (300 m)

CLIO (100 m)

LCGT (3 km)

Recycling mirror:

Increase effective

laser power

Standard optical configuration

Fabry-Perot arm cavity

Fabry-Perot arm cavity

Enhance GW signals

Laser Interferometer in Space• Signal increased - Due to longer interaction between GW and light - Cancellation of signals at higher frequencies• Noise reduced - Lower seismic noise and gravity gradient noise

Sensitivity improvedat lower frequencies

LISA• Arm length: 5,000,000km• Frequency range: 1 mHz - 0.1 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

10-18

10-24

10-22

10-20

10-4 10410210010-2

Frequency [Hz]

Stra

in [H

z-1/2]

LISA

DECIGO

Terrestrial detectors (e.g. LCGT)

Confusion Noise

moved above

LISA band To be movedinto TD band

Pre-conceptual designDifferential FP interferometer

Arm length: 1000 kmMirror diameter: 1 mLaser wavelength： 0.532 mFinesse: 10Laser power: 10 WMirror mass: 100 kgS/C: drag free3 interferometers

LaserPhoto-detector

Arm cavity

Drag-free S/C

Arm cavity

Mirror

Why FP cavity?

Frequency

Stra

in

Radiation pressure

noise f -2

Shot noiseShot n

oise f1

Transponder type(e.g. LISA)

Shot noise

Shortenarm length

Shot noise

f1

Radiation pressure

noise f -2

Transponder type(e.g. LISA) Shorten

arm length Implement FP cavity

Implement FP cavity

FP cavity type Better best- sensitivity

Drag free and FP cavity: compatible?

Mirror

S/C IS/C II

FP cavity and drag free : compatible?

Local sensor

ThrusterThruster

Mirror

Relative position between mirror

and S/C

S/C II S/C I

Drag free and FP cavity: compatible?

Local sensor

ThrusterThruster

Mirror

Relative position between mirror

and S/C

Actuator

Interferometer output (GW signal)

S/C II S/C I

No signalmixture

Orbit and constellation (preliminary)

Sun

Earth

Record disk

Increase angular resolution

Correlation for stochastic background

Science by DECIGO (1)

Formation of Super-

massive BH

Frequency [Hz]

Stra

in [H

z-1/2]

10-3 10-2 10-1 1 10 102 103

10-19

10-20

10-21

10-22

10-23

10-24

10-25

10-26

(1000 M◎ z=1)

BH binaryCoalescence

Radiation pressure noise

Shot noise

1 cluster

Science by DECIGO (2)

Frequency [Hz]

Stra

in [H

z-1/2]

10-3 10-2 10-1 1 10 102 103

10-19

10-20

10-21

10-22

10-23

10-24

10-25

10-26

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

Stra

in

Template (No Acceleration)

Real Signal ?Phase Delay～ 1sec (10 years)

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

Science by DECIGO (3)

Inflation(GW=210-16)Verification

of inflation

Frequency [Hz]

Correlation(3 years)

Stra

in [H

z-1/2]

10-3 10-2 10-1 1 10 102 103

10-19

10-20

10-21

10-22

10-23

10-24

10-25

10-26

Radiation pressure noise

Shot noise

1 cluster

Requirements 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.

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.

Thruster system should satisfy range, noise, bandwidth, and durability.

Roadmap200

7 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26Mission

Objectives

Test of key technologiesObservation run of GW

Detection of GW w/ minimum spec.Test FP cavity between S/C

Full GW astronomy

Scope

1 S/C1 arm

3 S/C1 interferometer

3 S/C,3 interferometer3 or 4 units

DICIGO Pathfinder(DPF) Pre-DECIGO

DECIGO

R&DFabrication

R&DFabrication

R&DFabrication

DECIGO Pathfinder (DPF)

Laser

PD

Floating Mirrors

Drag-free S/C

DECIGO DPF

30 cm

1,000 km

Shrink the arm lengthfrom 1,000 km to 30 cm

Conceptual design and Technologies to demonstrate

Thruster

Local Sensor

Floating mirrorStabilization

system

LaserActuator

Drag-free control system Laser source and stabilization system Control of Fabry-Perot interferometer Launch-lock system

Goal sensitivity of DPF

10–2 10–1 100 101 10210–18

10–17

10–16

10–15

10–14

10–13

10–12

10–11

10–19

10–18

10–17

10–16

10–15

10–14

10–13

10–12

Noi

se le

vel

[1/H

z1/2 ]

Frequency [Hz]

Shot noiseMirror thermal

Laser Radiation

Laser: 1064nm, 25mWFinesse: 100Mirror mass: 1kgQ–value of a mirror: 10 6

Cavity length: 10cm

pressure noise

Thruster noise

PM acceleration Noise

Geogravity Laser Frequencynoise

Dis

plac

emen

t Noi

se

[m/H

z1/2 ]

Expected sources

103 104 105 10610–1

100

101

102

Obs

erva

ble

Ran

ge

Mass [Msolar]

[kpc

, SN

R=5

]

Galactic Center

BH QNMBH Inspiral

JAXA’s Small science satellite series

• Plan to launch 3 small satellites between 2011 and 2015– using next-generation solid rocket booster

• Reduce time and cost by means of ‘Standard bus system’ – Bus weight : ~ 200kg, Bus power : ~ 800W– Downlink ~ 2Mbps, Data storage ~ 1GByte– 3-axes attitude control– SpaceWire-based data processing system

• We submitted a proposal for DPF

In June 2007, I attended the LIGO PAC meeting at Caltech, and we were invited to dinner at a Chinese restaurant.

We gainedmomentum!

DPF was selected as one of the 4 important mission candidates for small science satellite series run by JAXA/ISAS.

DPF S/C

Size : 900mm cubeWeight : 200kgSAP : 800W Battery: 50AHDownlink : 2MpbsDR: 1GByte3N Thrusters x 4

Stabilized Laser

Interferometer Module

Thruster Control Unit

Solar Paddle

Interfererometer Control Unit

Housing Control Unit

Mission Thrusters

Central Processing Unit

Bus Thrusters

Satellite Bus (‘Standard bus’ system)

DPF PayloadSize : 900mm cubeWeight : 100kgPower : 200WData Rate: 600kbpsMission thruster x16

Power SupplySpW Comm.

DPF Mission Outline

Orbit: Low-Earth (Altitude 500km), Sun-synchronous orbit (dusk-dawn)

Launcher: Single launch by M-V follow-on (solid rocket booster under development) PBS (Post-Boost stage) for fine orbit insertion

Launch: 2012 (target)Mission Lifetime: 1 year (nominal)

500km

DPF

Attitude Control: Gravity-gradient stab. Drag-free control with mission thrusters (Safe hold control by bus thrusters)

History and Future

2006 Nov. Submitted a proposal of DPF2007 Jun. Fortune cookie2007 Aug. Selected as a Pre-Phase-A mission R&D costs funded2008 Sep. Submitted Phase-A proposal2008 Dec. Hearing held for selecting the 2nd mission2009 Mar. 2nd mission will be selected

Pre-DECIGOPre-DECIGO

DECIGO

Arm length 100 km 1000 km

Mirror diameter 30 cm 1 m

Laser wavelength 0.532 m 0.532 m

Finesse 30 10

Laser power 1 W 10 W

Mirror mass 30 kg 100 kg

# of interferometers in each cluster

1 3

# of clusters 1 4

Sensitivity of Pre-DECIGO

10-24

10-23

10-22

10-21

10-20

10-19

10-18

10-17

10-16

10-15

Stra

in s

ensi

tivi

ty [1

/rH

z]

10-3 10-2 10-1 100 101 102 103

Frequency [Hz]

DPFDPFDPFDPF

NS-NS inspiral (@300Mpc)

pre-DECIGO

DECIGO

S/N~14 for NS-NS@300Mpc, 10-20 events/year

Interim organizationPI: Kawamura (NAOJ)Deputy: Ando (Kyoto)

Executive CommitteeKawamura (NAOJ), Ando (Kyoto), Seto (NAOJ), Nakamura (Kyoto), Tsubono (Tokyo), Tanaka (Kyoto), Funaki (ISAS), Numata (Maryland), Sato (H

osei), Kanda (Osaka city), Takashima (ISAS), Ioka (Kyoto)

Pre-DECIGO

Sato (Hosei)

Satellite

Funaki (ISAS)

Science, Data

Tanaka (Kyoto)Seto (NAOJ)

Kanda (Osaka city)

DECIGO pathfinderLeader: Ando (Kyoto)

Deputy: Takashima (ISAS)

Detector

Ando (Kyoto)

Housing

Sato (Hosei)

Laser

Ueda (ILS)Musya (IL

S)

Drag free

Moriwaki (Tokyo)

Sakai (ISAS)

Thruster

Funaki (ISAS)

Bus

Takashima (ISAS)

Data

Kanda (Osaka

city)

Detector

Numata (Maryland)

Ando (Tokyo)

Mission phase

Design phase

DECIGO-WGSeiji 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

1st InternationalLISA-DECIGO Workshop

• Nov. 12-13, 2008 @ ISAS, Sagamihara, Japan• Participants:

– Danzmann, Heinzel, Gianolio, Jennrich, Lobo, McNamara, Mueller, Prince, Stebbins, Sun, Vitale, …

• Accomplishments:– Mutual understanding– Kick-off of collaborations– Exposure of the missions to people in the neighboring fields

Collaboration with Stanford

• UV LED discharge for DPF• Other R&D for DECIGO

Summary

• DECIGO can detect GWs from the inflation as well as can bring us extremely interesting science.

• DPF has been selected as one of the important mission candidates for small science satellite series; they plan to launch 3 missions in 5 years starting from 2011.

Let DPF fly!

Possible breakthrough for3rd-generation detectors:

Displacement-noise free Interferometer

Kawamura and Chen, PRL, 93, (2004) 211103Chen and Kawamura, PRL, 96 (2006) 231102

Motivation Displacement noise: seismic Noise, thermal noise,

radiation pressure noise Cancel displacement noise shot noise limited

sensitivity Increase laser power sensitivity improved indefinitely

Frequency

Sens

itivi

ty

Displacement noise

Shot noise

Laser

PD

Diplacement noise

Cancel displacement noise

Increase laser power

GW and mirror motion interact with light differently

Difference outstanding forGW wavelength distance between masses

Mirror motionMirror motion

GW On propagation

On reflection

Light

Cancel motion of objects

CBBCABBA

　Motion of A, B, and C cancelled

　 GW signal remains

Clock

Why is it possible?# of MQ (4) ＞ # of DOF (3)

MQ: Measurable quantityDOF: Degree of freedom

Therefore a combination of MQs that is free from DOFs exists!

Clock noise?

CBBCABBA

　Motion: cancelled

　 Clock noise: not cancelled

Clock

Why?

　 # of DOF (Clock): 3　 # of DOF (Displacement): 3　 # of MQ: 4

Therefore it is not always possible to make a combination of MQs that is free from all the DOFs!

How can we cope with it?d: # of dimensions, N: # of Objects

# of DOF (Displacement) ： Nd# of DOF (Clock) ： N# of DOF (Total) ： N(d+1)# of MQ ： N(N-1)

If N(N-1)>N(d+1) i.e. N>d+2A combination of MQs that is free from D

OFs exists!

Displacement-noise free interferometer

• Propagation time measurement interferometer

• Motion of object displacement noise of mirrors

• Clock noise laser frequency noise

Example of DFI

Two 3-d bi-directional MZ

Take combination of 4 outputs

Mirror motion completely cancelled

GW signal remains (f 2)

Experiment (Ideal)One bi-directional MZ

GWMirror motion Laser

PD

GW Mirror motion

Extract

Experiment (Practical)EOM used for GW and mirror motion

GWMirror motion Laser

PDLaser

PD

～ ～Simulated mirror motion Simulated GW

Ideal　　　　　　　　　　　　　　　　Practical

Results

Mirror motion　　　　　　　　 GW signal

Mirror motion cancels outGW signal remains

Mirror motion to output

Difference

DifferenceGW signal to output

Sato, Kokeyama, Ward, Kawamura, Chen, Pai, Somiya, PRL 98 (2007) 141101

Possible breakthrough for3rd-generation detectors:

Juggling Interferometer

Motivation

10-8

10-9

10-10

10-11

10-12

10-13

10-14

10-15

10-16

10-17

10-18

10-19

10-201 10 100 　 Frequency [Hz]

Displacement [mHz-1/2]Seismic noise

Pendulum thermal noise

Radiation pressure noise

Shot noise

Limiting the low-frequency sensitivity

• Lower frequency gives higher GW signals.

• Suspension thermal noise and seismic noise are huge at low frequencies.

• What if we can remove suspension?

• Magnetic levitation is a kind of suspension.

• Free-fall experiment is just one shot.

km-class juggling interferometer

3 km

Laser

Fiber

Laser beam

Beamsplitter

Clamp

Mirror

Clamp

Simple Interferometer Simple Michelson interferometer

– FP cavity is not necessary because the sensitivity is limited by displacement noise at low frequencies anyway

No fringe lock– Fringe lock is not necessary because

intensity noise can be suppressed and no power recycling is necessary

Data processing 1Produce displacement signal (x)

from the two PD outputs

Dis

plac

emen

t

Time

Noise caused by juggling • x:

– Longitudinal position on release fluctuates• dx/dt:

– Longitudinal velocity on release fluctuates– Angular velocity on release fluctuates, whic

h couples with beam off-centering• d2x/dt2:

– Above two effects couple with each other• x, dx/dt, d2x/dt2 are constant in each seg

ment

Data processing 2• In each segment, calculate <x>, <dx/dt

>, <d2x/dt2>• Remove them from the data

Loss of GW signal• A part of GW signal especially below 1

Hz is lost during the data processing 2.• So is a part of any noise.• S/N remains the same?

S/N degraded below 1 Hz

Shot noise after data processing

Original shot noise

0.1 　　　 1 　　 　 10 　　　　 Frequency [Hz]

10-15

10-16

10-17

10-18

10-19

10-20

Displacement [mHz-1/2]

Juggling interferometer prototype

Moving up and

down

TimePo

sitio

n

~ 2

m

Releas

e Hold

Continually

Freely falling

~ 1 sec

Clamp

Releas

e Hold

Releas

e Hold