Space Gravitational Wave Detection in China

Yue-Liang Wu

University of Chinese Academy of Sciences (UCAS)

Kavli Institute for Theoretical Physics China (KITPC/ITP-CAS)

On behalf of Working Group on Space GWD/CAS

First eLISA Consortium Meeting

APC-Paris, France, Oct. 22-23, 2012

Strategic Goal of Space Science in China: A Roadmap to 2050

-----------------------------------------------------------

Original breakthroughs should be made in directly detecting black hole, dark matter, dark energy, gravitational waves, …….

-- Space Sciences & Technology

in China: A Roadmap to 2050,

(Edt: H.D. Guo, J. Wu

Science Press & Springer, Beijing, 2010)

Space Science Strategy Pioneer Program, (SSSPP/CAS)

• Leading Group

Director: H.J. Yin (Vice-President of CAS)

• National Scientific Committee of Space Science

Chairman: H.J. Yin

• Office of SSSPP

Director: Y.J. Yu (HQ CAS)

• National Space Science Center

Chairman: J. Wu (Director of Space Science &

Application Center)

Studies on GW Detection in ChinaMany workshops and meetings have been held in China

• Ground GW detection:

Australia-China collaboration

• ASTROD: suggested by Prof. W.D. Ni

• Space GW Detection of China (2008-2011):

Feasibility study on Space G-W Detection.

A suggestion on SGD program similar to LISA in

frequency range f ～ 1.0-10-2 Hz

• Working group on SGD mission for joining the NGO Program (2012 - )

World-wide Future GW detection projects

Suggestion of Space GWD in China

• Feasibility study based on ALIA Mission concept (2008-2010).

• Preliminary studies phase of CAS project for began and a mission design (2010-2012).

• Ground based experiments in key technologies and theoretical studies. Accepted as a part of national program in 2011 and will be started in the near future after a starting review (2011-2015) .

Chinese Mission Options (Inst. Appl. Math./CAS)

Mission Design

Assumptions:1. Sensitivity of inertial sensor one order

better than that of LISA

(at higher frequency window)

1. Suppress shot noise by increasing laser power and diameter of telescope

~1.5 order more sensitivity than LISA. Sensitivity floor shifts to the right.

Baseline Design Parameters (Peter Bender , CQG, 21, S1203 (2004))

Options ( Inst. Appl. Math., CAS)

3L and 3H are currently preferred as far as technology development is concerned

Main Scientific Purpose

Overlapped with LISA

• Sensitivity floor shifts to the right. • Enhanced Intermediate mass

black holes (IMBH) detection

• Light seed Population III remnants

Almost equal mass coalescence

(High redshift)

• Intermediate mass ratio spiral

(Low redshift)

Overlapped with BBO/DECIGO The major purpose of space

gravitational wave detection in bandwidth between 0.1 and 1.0 Hz is to search for the stochastic back ground of gravitational waves coming from the early university

• Primordial Gravitational Wave Background (inflation, electroweak transition, Population III stars core collapse)

• Bursts from hypothetical cosmological structures like cosmic string and other topological defects in the early Universe

Better IMBH Detection – Extra Sciences on offer

Main difference from LISA Sensitivity floor shifts to the right.Enhanced Intermediate mass black holes (IMBH) detection

• Light seed Population III remnants• Almost equal mass coalescence (High redshift)• Intermediate mass ratio spiral (Low redshift)

Working Group on SGWD/CAS (2012)Heads W.R. Hu (Institute of Mechanics), Y.L. Wu (Univ. of Chinese Academy of Sciences, UCAS).

Members L.Q. Peng (Bureau of Basic Research Sciences), C.F. Qiao and Y.S. Pu (Univ. of Chinese Acad. of Sci.), R.Q. Lau (Institute of Applied Math.) , G. Jin and Q. Kang (Institute of Mechanics), Y.X. Nie and Z.Y. Wei (Institute of Physics), M. Li and Y.Z. Zhang (Institute of Theoretical Physics), S.N, Zhang (Institute of High Energy Physics) Z.L. Zhou and Y.T. Zhu(National Astronomy Observatory), M.S. Zhan and L.S. Chen (Wuhan Institute of Phys. &

Math.).

Possibility on Joining NGO Program Telescope of NGO (Nanjing Institute of

Astronomy and Optics Technology, CAS)

Collaboration with MP Institute for Gravitational Physics on Laser Interferometer (Institute of Mechanics, CAS)

Collaboration with Trento University for inertial sensors (Huazhong University of Sci. & Tech.)

Others

Nanjing Institute of Astronomical & Optics Nanjing Institute of Astronomical & Optics Technology –Space TelescopeTechnology –Space Telescope

LAMOSTLAMOST Antarctic Antarctic telescopetelescope

SiCSiCMirroMirrorr

ZeroduZerodur r mirrormirror

Critical Requirements for the Critical Requirements for the Telescope SubsystemTelescope Subsystem

Parameter Derived From NGO

1 Wavelength 1064 nm

2Net Wave front quality of as built telescope subs system over science field of view

Pointing 20 RMS

3Telescope subsystem optical path length stability under specified environment

Path length Noise/ Pointingwhere 0.0001 < f < 1 Hz

1 pm = 10-12 m

4 Field-of-View (Acquisition) Acquisition +/- 200 rad

5 Field-of-View (Science) Orbits+/- 7 rad out-of-plane2

+/- 4.2 rad in-plane

6 Transmitted beam diameter on primary mirror Shot noise/ Pointing 0.92·D

7 Entrance Mirror Diameter Noise/ pointing 200 mm

8 Entrance Pupil Pointing Entrance of beam or primary

11 Location of image of primary mirror (exit pupil) Pointing ~10 cm (on axis) behind primary mirror

12 Pupil distortion SNR 10%

13 Beam size on bench short arm interferometer 5 mm

14 Mechanical length 350 mm15 Optical efficiency Shot noise >0.85

16 Scattered Light Displacement noise < 10-10 of transmitted power

17 Telescope spacer variation 2.5 microns

1 pm / Hz 10.003

f

4

Space TelescopesSpace Telescopes— — Utilize the Goddard Space Flight Center designUtilize the Goddard Space Flight Center design

Material and FabricationMaterial and Fabrication• Mirrors--- Zerodur• Telescope spacer– SiC , Asymmetric Quad-Pod design

• Wavefront quality realized in mirror lab.

Stability Test and MeasurementsStability Test and Measurements

Cooperation Between AEI and IM/CAS

• Jointly develop the space laser interferometer for NGO ;

• Share the future space laser interferometer duty in NGO mission.

Space Interferometer on the earth base

Institute of Mechanics/CASInstitute of Physics/CASWuhan Institute of Phys. & Math./CASHUST

Further Ground Based Experiments

1 、 Measurement of distance variation;

2 、 Noise evaluation;

3 、 Pointing control;

4 、 Phase lock;

5 、 Ranging tone system demo;

6 、 Sideband-sideband scheme demo;

7 、 TDI demo;

Two M-Z interferometers (equal arm)

Heterodyne detection

Laser metrology Demonstration System @ IMECH CAS

Laser wave length 633nm

Isolated base

Clean room: class 1000

Thermal stabilized by air-condition

Offset frequency from 10kHz to 500kHz

Laser metrology Demonstration System @ IMECH CAS

Noise Curve in Noise Curve in Power Spectra Power Spectra DensityDensity

With Mirror-D fixed

Mirror-D moved sinusoidally, with a period 100s.

0.1 - 0.5 nm/Hz1/2 within frequency band between 0.15 m Hz and 0.375 Hz

1 - 3 nm/Hz1/2 between 0.15m Hz and 0.01 HzLower than 1 nm/Hz1/2 within from 0.01 Hz to 0.375 Hz

HUST

HUST

Goal of cooperative research•Modeling and evaluation of the performances of inertial sensors for GW missions•Development of ground-based testing facilities, and research on inertial sensors•Design of some engineering components and their performance verification•Training of research groups

Contents of cooperative research•Modeling and the analysis of spurious forces •Developing torsion pendulum for ground-based tests•Experimental verification of the noise model and sensor performance•Coupling between interferometer and inertial sensor•Coupling between inertial sensor and drag-free control

Cooperation Agreement between HUST and Univ. Trento

Cooperation Agreement between HUST and Univ. Trento

28

10-14 Nm/Hz1/2

Univ. Trento, ItalyPRL 91 (2003) 151101PRL 103 (2009) 140601PRL 108 (2012) 181101

Progress of Inertial sensor of LISA Pathfinder Performance research of inertial sensor using torsion pendulums Push to develop the inertial sensor engineering model

29

•To develop a two-stage pendulum to test performances of inertial sensor•The facility can be used to simulate 2D motions of the proof mass, which is important to investigate cross-coupling of PM

Progress of HUST

9*10-14Nm/Hz1/2

Tu et al., CQG 27 (2010) 205016Zhou et al., CQG 27 (2010) 175012

Inertial Sensor Development in HUST

fiber

frame & TM

micro-operation platform

turntable

Inertial sensor

box

Torsion Pendulum

Sensitive to torque

Torsion Balance Sensitive to direct force

Sensitive Direction

d0=152 um

Two space experiments have been

scheduled

School of Physics , HUST, China

Inertial SensorHuazhong University of Sci. & Tech. (HUST)

Next-step:Fused-fiber suspension, thermal limit: 1fNm / √Hz at 2mHzTo determine differential shape and material proof mass (PM)To measure the effects of PM with temperature, electric, magneticTo investigate the cross-coupling between the DoF of PM

Progress:Two-stage torsion pendulum, (Liu et al., CQG 2010)10-10m/s2/√Hz for small gap 0.1mm (Tu et al., CQG 2010)

1 0 5 1 0 4 0 .0 0 1 0 .0 1 0 .1 11 0 1 7

1 0 1 6

1 0 1 5

1 0 1 4

1 0 1 3

F req u en cyH z

S N12 NmHz12 s u s p e n s io n f ib e r

g o ld w ire

Others

To be considered and discussed

Prospect

• Step I (2011~2015)

Ground studies on theoretical analyses and key technology

• Step II (2016~2020+)

Space technology for a satellite of key technology experiment

• Step III (2020+ ~ 2030+)

Satellite of GWD/CN or joining NGO

Thank You!