International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )

DECIGO PathfinderDECIGO Pathfinder

Masaki Ando Masaki Ando (Department of Physics, The University of Tokyo)(Department of Physics, The University of Tokyo)

and DECIGO Pathfinder working and DECIGO Pathfinder working GroupGroup

International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 2

Introduction (1)Introduction (1)

DECIGO roadmap 　

LISALPF

Ad. LIGOLCGT

International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 3

DECIGO-PF (1)DECIGO-PF (1)

DECIGO Pathfinder (DPF)

DECIGO-PF　　 One small satellite (Weight: ~200-300kg, Orbit: around the earth) 10cm Fabry-Perot cavity formed by free masses Stabilized laser source Drag-free control system

Local Sensor

Actuator

Thruster

Gravitational-wave observation　　　 (5) Observation for low-frequency (0.1-1Hz) GWs　　 Mid.-scale BHs at the Galactic center 　

Test and demonstration for DECIGO　　　 (1) Drag-free control system　　　 (2) Laser source and its stabilization system (3) Control of Fabry-Perot interferometer (4) Launch-lock system

International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 4

DECIGO-PF (2)DECIGO-PF (2)

DPF diagram

Fabry-Perot interferometer 　 Finesse : 100 　 Length : 10cm 　 Test mass : 1kg Signal extraction by PDH

Laser source Nd:YAG laser (1064nm) Power : 25mW Freq. stab. by reference cavity

Drag-free control Local sensor signal 　　 Feedback to thrusters/wheels

Mission weight : ~100kgMission space : ~90 x 90 x 90 cm

International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 5

DECIGO-PF (3)DECIGO-PF (3)

DPF sensitivity

Satellite mass : 100kg, Area: 1m2

Altitude: 750kmThruster noise: 0.1μN/Hz1/2

Laser source : 1064nm, 25mW IFO length : 10cmFinesse : 100, Mirror mass : 1kgQ-factor : 105, Substrate: Fused SilicaTemperature : 293K

(Preliminary parameters)

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

No

ise

lev

el

[1

/Hz1/

2 ]

Frequency [Hz]

Shot noise

Mirror thermal

Laser Radiation

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

Cavity length: 10cm

pressure noiseThruster noise

PM acceleration Noise

Geogravity

Laser Frequencynoise

Dis

pla

ce

me

nt

No

ise

[m

/Hz1/

2 ]

International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 6

DECIGO-PF (4)DECIGO-PF (4)

DPF orbit

DP

F

Selection of DPF orbit　 　 Launch chance (Cost, Launch window) Operation (Power supply, Telemetry)　　 Stability, NoisesLow-earth orbit

Altitude 750km Polar sun synchronous orbit

750km

No eclipse Full-time operationHigher altitude will be desirable　　 to reduce the effect of the earth (Earth’s gravity, terrestrial magnetism, residual atmosphere)Depends on launch chance

Earth

Sun

International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 7

DECIGO-PF (5)DECIGO-PF (5)

Gravity-gradient noise Global gravity field model Public data obtained by GRACE　 Up to 150th-order in spherical harmonicsSatellite velocity of 5km/sec Estimate the noise spectrum Assume 2% vertical-horizontal coupling

Cut-off at 0.03Hz: originates in the model resolution Unknown at higher frequencyThis will not be a problem: higher-order contribution will be negligible order of ~(Re/r) n

Observe gravity field with higher resolution?

10–2 10–1 100 101 10210–18

10–17

10–16

10–15

10–14

10–13

10–12

10–11

Ac

ce

lera

tio

n N

ois

e [

m/s

2 /Hz1/

2]

Frequency [Hz]

Shot noise

Mirror th

ermal

Laser Radiationpressure noise

Radiation Pressure

of the Sun

PM acceleration Noise

Earth's Tidal force

DPF total

International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 8

DECIGO-PF (6)DECIGO-PF (6)

Geomagnetic noise

Fluctuation in geomagnetic field Public data at Esashi observatory 1 sample/min data Extrapolate for higher frequency

Two effect by geomagnetic field: Satellite motion in magnetic field　 Fluctuation in geomagnetic field

10–3 10–2 10–1 10010–6

10–4

10–2

100

102

104

Mag

net

ic n

ois

e [

nT/

Hz1

/2]

Frequency [Hz]

(N–S Direction)

(Vertical Direction)

Geomagnetic FieldFluctuation

S/C motion

S/C Motion

Geomagnetic field model IGRF-10 model (10th generation of International

Geomagnetic Reference Field) Altitude 750km Satellite velocity of 5km/sec

Satellite self-field

Effect of geomagnetic field: smaller than satellite self-field ~10-7 T noise level ~ 1.5 x 10-16 m/s2/Hz1/2

10–2 10–1 100 101 10210–18

10–17

10–16

10–15

10–14

10–13

10–12

10–11

Ac

ce

lera

tio

n N

ois

e [

m/s

2 /Hz1/

2]

Frequency [Hz]

Shot noise

Mirror th

ermal

Laser Radiationpressure noise

Radiation Pressure

of the Sun

PM acceleration Noise

Earth's Tidal force

DPF total

Magnetic-field noise

International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 9

DECIGO-PF (7)DECIGO-PF (7)

Survey of noise sources

Residual Gas

Thermal radiation

Magnetic field

Laser freq. noise

Force Acceleration Acceleration noise Displacement noise

International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 10

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]

DECIGO-PF (8)DECIGO-PF (8)

Comparison with other detectors

LCGT DECIGO

Galactic binaryForeground noise

Core-collapse super nova

NS inspiral

Inspiral ofMassive BH

Galactic binary

ScoX-1 (1yr)Pulsar

　　 (1yr)

LISA

Gravity-gradient noise for terrestrial detectors

DPF limit

Only a little observation data at low-frequency band　　　 Doppler tracking: h ~10-15 　 (10-4-10-2 Hz) Pulsar timing: h ~10-14 　 (10-8 Hz)

GWs from Early universe (gw=10-14)

International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 11

DECIGO-PF (9)DECIGO-PF (9)

DPF targetsQuasi-nomal mode oscillation of massive BH

Binary inspiral of mid.-scale BHs

10–2 10–1 100 101 10210–17

10–16

10–15

10–14

10–13

10–12

GW

ch

arac

teri

stic

am

plit

ud

e

Frequency [Hz]

Dopplar105Mo

DPF

(Ob

s.

ba

nd

= C

en

ter

fre

qu

en

cy

)

tracking

BH QNM(1Mpc)

BH chirp(103Mo, 10kpc)

DPFFundamental noise

106Mo

104Mo

Estimated noises

103 104 105 10610–1

100

101

102

Ob

serv

able

Ran

ge

Mass [Msolar]

[kp

c, S

NR

=5

]

Galactic Center

BH QNM

BH Inspiral

Events at Galactic center will be detectable with SNR~5

h ~ 10-15 , f ~ 0.3 Hz Distance 1Mpc, m = 105 Msun

h ~ 10-15 , f ~ 4 Hz Distance 10kpc, m = 103

Msun

International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 12

DPF status (1)DPF status (1)

Brief history

2004 December　　　 Call for suggestions of small satellite mission by JAXA2005  January 　　　 Submit a proposal of small GW detector mission ~30 missions were submitted2006 October Call for proposals of small satellite mission by JAXA2006 November　　　 Submit a proposal of GW-detector satellite as DECIGO pathfinder (DPF) 16 missions were accepted as working groups (10 science, 6 engineering missions), including DPF2007 April Review meeting for these missions2007 August DPF has been selected as one of 5 Pre-Phase-A missions R&D costs have been funded

International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 13

DPF status (2)DPF status (2)

DPF status

JAXA is planning to launch 3 small satellite by the year 2013 using next-generation solid rocket booster under developmentReduce time and cost by means of ‘Standard bus system’ Preliminary parameters Bus weight : ~ 200kg, Bus power : ~ 900W 　 Downlink ~ 4Mbps, Data storage ~ 1GByte 3-axes angular control

1st mission (2011) has been decided to be TOPS (Space telescope mission for planet observation)

2nd and 3rd mission will be selected by 2009 March

Candidate missions DPF: GW observation DIOS: X-ray telescope for dark baryon investigation ERG: Plasma and particle detector for geo-space investigation Satellite for Magnet-plasma sail technology demonstration, …

International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 14

DPF status (3)DPF status (3)

R&D plan for DPF

Laser frequency stabilizationMirror and its housing (local sensor, actuator, launch-lock

system)Micro thrusterDrag-free control simulationDetailed design and noise investigation

(Under discussion)

Required to submit Phase-A proposal by 2009 MarchR&D for core technologies

Target: launch in 2012 or 2013 as 2nd or 3rd standard small satellite of JAXA

International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 15

SummarySummary

　　 One small satellite (Weight: ~200-300kg, Orbit: around the earth) 10cm Fabry-Perot cavity formed by free masses Stabilized laser source Drag-free control system

Local Sensor

Actuator

Thruster

Gravitational-wave observationTest and demonstration for DECIGO

DECIGO pathfinder: First demonstration satellite for DECIGO

Selected and funded as one of the candidates of JAXA’s small satellite missions Hoping to be launched in 2012 - 2013

0.1Hz-1Hz bandBH QNM and Mid.-BH inspiral at Galactic

center

International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 16

TopicsTopics

Steps for DPFSmall module to be launched in 2008

SDS-I : Small (~100kg) satellite for demonstration of space technologies To be launched in 2008 summer by H-IIA as piggy-back satellite of GOSATSWIM: very small GW detector module will be included in SWIM (SpaceWire Interface demonstration Module)

Small test-mass moduleSmall test-mass module

Test mass

Photo sensor

Coil-magnet actuator

Free-falling experiment using balloon

BOV 2.5 : Free-falling vehicle from large balloon ~30 sec free-falling streach from 40km altitude Drag-free control system using gas-jet thrustersPrototype of SWIM is included in BOV

Experiment module Diameter ~ 28cm

International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 17

　　　　 　　　 　 EndEnd