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DECIGO Pathfinder
Masaki Ando
(Department of Physics, The University of Tokyo)
and DECIGO Pathfinder working Group
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )
Introduction (1)
DECIGO roadmap
LPF
LISA
Ad. LIGO
LCGT
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 2
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
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
Gravitational-wave observation
Actuator
Thruster
(5) Observation for low-frequency (0.1-1Hz) GWs
Mid.-scale BHs at the Galactic center
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 3
DECIGO-PF (2)
DPF diagram
Mission weight : ~100kg
Mission space : ~90 x 90 x 90 cm
Laser source
Nd:YAG laser (1064nm)
Power : 25mW
Freq. stab. by reference cavity
Drag-free control
Local sensor signal
 Feedback to thrusters/wheels
Fabry-Perot interferometer
Finesse : 100
Length : 10cm
Test mass : 1kg
Signal extraction by PDH
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 4
DECIGO-PF (3)
DPF sensitivity
(Preliminary parameters)
]
1/2
PM
–13
10
ac
og
Ge
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ler
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ty
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s
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Th
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ter
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–13
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–15
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No
Laser
Frequency
10
is
La
se e
noise
–17
prr R
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a
es d
Shot noise
su iat
–18
re ion
Mirror
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therma 10
ise
l
–19
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0
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ise
no
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rav
Noise level [1/Hz
Cavity length: 10cm
Laser: 1064nm, 25mW
Finesse: 100
Mirror mass: 1kg
Q–value of a mirror: 10
–12
10
1/2
–12
10
Displacement Noise [m/Hz
–11
10
]
Laser source : 1064nm, 25mW
Satellite mass : 100kg, Area: 1m2
IFO length : 10cm
Altitude: 750km
Finesse : 100, Mirror mass : 1kg
Thruster noise: 0.1μN/Hz1/2
Q-factor : 105, Substrate: Fused Silica
Temperature : 293K
Frequency [Hz]
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 5
DECIGO-PF (4)
DPF orbit
Selection of DPF orbit
Launch chance (Cost, Launch window)
Operation (Power supply, Telemetry)
Stability, Noises
750km
Sun
No eclipse
 Full-time operation
Higher altitude will be desirable
to reduce the effect of the earth
(Earth’s gravity, terrestrial magnetism,
residual atmosphere)
DPF
Low-earth orbit
Altitude 750km
Polar sun synchronous orbit
Earth
Depends on launch chance
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 6
DECIGO-PF (5)
Gravity-gradient noise
Cut-off at 0.03Hz:
originates in the model resolution
 Unknown at higher frequency
This will not be a problem:
Global gravity field model
Public data obtained by GRACE
Up to 150th-order
in spherical harmonics
Satellite velocity of 5km/sec
2
Acceleration Noise [m/s /Hz
1/2
]
 Estimate the noise spectrum
Assume 2% vertical-horizontal coupling
higher-order contribution will be negligible
order of ~(Re/r) n
Observe gravity field
with higher resolution?
–11
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Earth's Tidal force
–12
l
10
PM acceleration Noise
–13
10
al
m
se
r
i
the
no
r
t
o
ro
Sh Mir
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F
P
D
ta
to
Ra
di
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of on P
th re
e
Su ssu
n re
Laser Radiation
pressure noise
–18
10
–2
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–1
10
0
10
1
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10
Frequency [Hz]
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 7
DECIGO-PF (6)
Geomagnetic noise
1/2
Magnetic noise [nT/Hz
Two effect by geomagnetic field:
]
4
Satellite motion in magnetic field
Fluctuation in geomagnetic field
Geomagnetic field model
IGRF-10 model
(10th generation of International
Geomagnetic Reference Field)
Altitude 750km
Satellite velocity of 5km/sec
Effect of geomagnetic field:
smaller than satellite self-field ~10-7 T
 noise level ~ 1.5 x 10-16 m/s2/Hz1/2
Satellite
self-field
0
10
–2
10
Geomagnetic Field
Fluctuation
S/C Motion
(Vertical Direction)
–4
10
–6
–2
–1
10
0
10
10
1/2
]
Frequency [Hz]
2
Public data at Esashi observatory
1 sample/min data
 Extrapolate for higher frequency
S/C motion
(N–S Direction)
2
10
10 –3
10
Acceleration Noise [m/s /Hz
Fluctuation in geomagnetic field
10
–11
10
Earth's Tidal force
–12
l
10
PM acceleration Noise
–13
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t n ror t
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Sh Mir
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DP
ta
to
Ra
di
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of on P Magnetic-field noise
th re
e
Su ssu
Laser Radiation
n re
pressure noise
–18
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–1
10
0
10
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Frequency [Hz]
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 8
DECIGO-PF (7)
Survey of noise sources
Force
Acceleration
Acceleration noise
Displacement noise
Magnetic field
Residual Gas
Thermal radiation
Laser freq. noise
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan ) 9
DECIGO-PF (8)
Comparison with other detectors
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)
–16
Strain [1/Hz
1/2
]
10
–18
10
Inspiral of
Massive BH
DPF limit
LISA
NS inspiral
Galactic binary
Core-collapse
super nova
–20
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Galactic binary
Foreground noise
–22
10
DECIGO
–24
10
GWs from
Early universe
(Wgw=10-14)
ScoX-1
(1yr)
Pulsar
(1yr)
LCGT
Gravity-gradient
noise for terrestrial detectors
–26
10
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0
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Frequency [Hz]
2
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International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )10
DECIGO-PF (9)
DPF targets
(Obs. band = Center frequency)
(1M pc)
6
10 Mo
–15
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BH chirp
Dopplar
tracking
5
3
(10 Mo, 10k pc)
10 Mo
–16
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DPF
Fundamental noise 104Mo
–17
Observable Range
DPF
Estimated noises
–14
10
10
Binary inspiral of mid.-scale BHs
h ~ 10-15 , f ~ 4 Hz
Distance 10kpc, m = 103 Msun
BH QNM
–13
10
[kpc, SNR=5]
h ~ 10-15 , f ~ 0.3 Hz
Distance 1Mpc, m = 105 Msun
GW characteristic amplitude
Quasi-nomal mode
oscillation of massive BH
–12
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–1
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Frequency [Hz]
1
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2
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BH QNM
BH Inspiral
1
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Galactic Center
0
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–1
Events at Galactic center
will be detectable with SNR~5
10
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Mass [M solar]
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )11
DPF status (1)
Brief history
2004 December
Call for suggestions of small satellite mission by JAXA
2005 January
Submit a proposal of small GW detector mission
~30 missions were submitted
2006 October
Call for proposals of small satellite mission by JAXA
2006 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 DPF
2007 April
Review meeting for these missions
2007 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 )12
DPF status (2)
DPF status
JAXA is planning to launch 3 small satellite by the year 2013
using next-generation solid rocket booster under development
Reduce 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 )13
DPF status (3)
R&D plan for DPF
(Under discussion)
Required to submit Phase-A proposal by 2009 March
R&D for core technologies
Laser frequency stabilization
Mirror and its housing (local sensor, actuator, launch-lock system)
Micro thruster
Drag-free control simulation
Detailed design and noise investigation
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 )14
Summary
DECIGO pathfinder:
First demonstration satellite for DECIGO
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
Test and demonstration for DECIGO
Gravitational-wave observation
0.1Hz-1Hz band
BH QNM and Mid.-BH inspiral at Galactic center
Selected and funded as one of the
candidates of JAXA’s small satellite missions
Hoping to be launched in 2012 - 2013
Actuator
Thruster
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )15
Topics
Steps for DPF
Small module to be launched in 2008
Small test-mass module
Test
mass
SDS-I :
Small (~100kg) satellite
for demonstration of space technologies
To be launched in 2008 summer by H-IIA
as piggy-back satellite of GOSAT
SWIMmn:
very small GW detector module will be included
in SWIM (SpaceWire Interface demonstration Module)
Photo
sensor
Coilmagnet
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 thrusters
Prototype of SWIMmn is included in BOV
Experiment
module
Diameter ~ 28cm
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )16
End
International Conference on Topics in Astroparticle and Underground Physics (Sept. 11, 2007, Sendai, Japan )17