Coevolution of Black Holes-Galaxies and Space Detection of Gravitational Waves

Transcription

1 Coevolution of Black Holes-Galaxies and Space Detection of Gravitational Waves Yun Kau Lau (Runqiu Liu) Institute of Applied Maths and Morningside Center of Maths, Chinese Academy of Sciences, Beijing. Talk given on behalf of the Gravitational Wave Working Group, Chinese Academy of Sciences. APCTP, Korea,

2 Outline of the talk Ongoing development of space detection of gravitational wave program in the Chinese Academy of Sciences. Feasibility study ( ) (commissioned by the National Space Center, CAS) Scientific case study Prototypes development

3 Strategic goal of space science in China: a roadmap to Space sciences & technology in China: A roadmap to Science Press & Springer, Beijing, 2010

4 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 and gravitational waves,.

5 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 and gravitational waves,.

6 Detection of gravitational wave in space working group Coordinators: Wenrui Hu, Gang Jin (National Microgravity Laboratory, Institute of Mechanics ) Yueliang Wu (University of Chinese Academy of Sciences) Member Institutes participating in the group: Academy of Mathematics and Systems Science, Institute of high Energy Physics, Institute of Mechanics, Institute of Physics, Institute of Theoretical Physics, Nanjing Institute of Astronomy and Optics, National Astronomical Observatory, University of Chinese Academy of Sciences, University of Science and Technology of China, Hefei, Wuhan Institute of Physics and Mathematics.

7 Development of the working group Objectives of the working group: Lay the foundation for future development. Promote space gravitational wave detection research in China and international collaboration at the scientific level. Preliminary mission design Understand the potential of scientific discoveries Anatomy of the key technologies involved A mission study on Satellite Gravity and laser interferometry Feasibility Study of GW detection in space between the CAS working group and elisa scientific working group Prototypes development Promote collaboration on the elisa project between CAS and ESA.

8 Dual tracks of development Develop a Chinese mission of our own Contribute 20% to elisa telescope, part of inertial sensors, optical bench, escape orbit launcher, others...

9 Roadmap Grace II ( nm) temporal variation of earth gravity field Space detection of GW (5-8 pm)

10 Earth science mission design Expected range of key parameters for instruments design Distance between two S/Cs: km Altitude of orbit in relation to measurement sensitivity: km Drag free performance residual acceleration ~10-12 m/s 2 /Hz 1/2 (0.1Hz) Precision of laser metrology: μm ~ 100nm/Hz 1/2 (0.1Hz) Prospective Science Drivers Hydrology (especially in Asia) Climate change Seismology

11 laser metrology 100nm

12 laser metrology:100nm

13 Hydrology Simulation over Asia Trend of water thickness change computed using the GLDAS Model ( to ): 1 degree by 1 degree (Lei Wang, C.K.Shum)

14 Main theme of the Feasibility Study Preliminary Mission Concept Study Understand the potential of scientific discoveries Anatomy of the key technologies involved. Guiding Principles for the study: 1. A 30+ years time frame. 2. China makes significant contribution to the nascent field of Gravitational Wave Astronomy. 3. REALISTIC! --- technologically viable for China. 4. Need a long term vision in science objectives.

15 World wide future GW detection projects

16 Mission design ( ) First problem to be addressed: Determination of the measurement bandwidth and the corresponding science driver Lower freq. WD binaries confusion Higher freq. 0.01Hz or even 0.1Hz makes more sense. Technology viability adopt the simplest geometric (triangular) configuration Go to higher frequencies by shortening armlength.

17 Gravitational Wave Sources (mhz 1 Hz) Astrophysical: LISA sources with frequency above mhz Intermediate mass black holes (IMBH) Almost equal mass coalescence (High redshift) Intermediate mass ratio inspiral (Low redshift) Rare and uncertain events ---supernovae, black holewhite dwarf, black hole-neutron star binaries Burst events parabolic or hyperbolic encounter of a black hole with a star. Cosmological 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 Unmodelled sources

18 Gravitational Wave Sources (mhz 1 Hz) Astrophysical: LISA sources with frequency above mhz Intermediate mass black holes (IMBH) Almost equal mass coalescence (High redshift) Intermediate mass ratio inspiral (Low redshift) Rare and uncertain events ---supernovae, black holewhite dwarf, black hole-neutron star binaries Burst events parabolic or hyperbolic encounter of a black hole with a star. Cosmological 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 Unmodelled sources Main difference from LISA!

19 High Redshift IMBH versus Cosmic Structure Evolution First luminous star. End the dark age. z~30. Cosmic Structure began to develop. Dawn of the complexity of the Universe

20 IMBH as Heavy Pop III Remnant Pop III stars Almost metal free. Main sequence mass loss is insufficient, very large core just before collapse. ~100Msun<m<1000Msun (Abel et al. Science, 2002) Fate of star depends on mass: M< 140 Msun: SN Stellar BH M~ Msun: e-e+ instability explosion, no remnant (like that triggered SN 2006gy) M>260 Msun: Main Seq no SN direct collapse to IMBH M>150 Msun (Heger, Woosley, ApJ, 2003)

21 Characteristic Merger Frequencies of IMBHB at ISCO: M: total mass IMRI Pop III Inspiral signals of IMBH merger falls 1/100 Hz regime

22 Limitation of LISA LISA misses out on the IMBH binaries FT of signal in unit of per Hz SNR purple green green dashed LISA

23 Strain [Hz -1/2 ] LISA Gap LIGO and ground based Detectors Motivation of our work: Understand the IMBH gravitational wave sources around the 0.1 Hz window Frequency [Hz] Questions to be Addressed What are and the corresponding event rates? What science can the mission make significant contribution? How different is that from the LISA mission?

24 In Search of Binary IMBHs in the Hierarchical Structure Formation Process A Monte Carlo black hole merger simulaton Realization of EPS formula and semi-analytical dynamics recipes Preliminary results based on light hole seeding: 150M holes seeding at z=20, 3.5σhalos black hole spin evolution included two possible accretion recipes considered: prolonged accretion vs. chaotic accretion epsilon varies as a function of black hole spin, with a extreme Kerr limit of 0.4 efficient gaseous friction and spin alignment assumed moderate final gravitational radiation recoil < M Halo <10 15 M, 220 merger trees, (Volonteri, 2003)

25 Feasibility study based on the mission concept of ALIA ( )

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27 A Tug of War between science and technological feasibility! Sub-picometer precision requirement in laser metrology!!

28 Mission Descope Science merit vs technological feasibility

29 Instrument sensitivity

30 Detections Distributions Simulated Prior to merger 1yr observation assumed, single Michelson SNR>7

31 Descoped mission selected

32 Conservative prospective detection rates from the simulation lower upper single Michelson SNR threshold of 7. levels of extragalactic compact binary foreground ( Farmer & Phinney )

33 Better guaranteed detection rate on cluster harbored IMRIs IMBHs form in f_tot of all globular clusters ν_0: capture rate of a 10 solar mass black hole by the central IMBH

34 World wide Future GW detection projects

35 Chinese Mission Options

36 Sciences overlapping with LISA

37 Enhanced detection performance on IMBH

38 Better IMBH Detection Extra Sciences on offer Main difference from LISA Sensitivity floor shifts to the right. Enhanced Intermediate mass black holes (IMBH) detection

39 Mass threshold for light seed black hole detections

40 Redshift threshold with given mass of black holes

41 Detection range for almost equal mass IMBH-IMBH coalescence Angle averaged detection range under a single Michelson SNR threshold of 7 for 1:4 mass ratio IMBH binaries.

42 Detection range for IMRI

43 Detection range for IMRI As a given improvement in the detection range results in a cubic increase in the detection rate:

44 Preliminary mission design Descope options picked out and evaluated With the working band slightly shifted to the right and very moderate improvement in design parameters, attractive science on IMBH is to be expected.

45 Preliminary orbit design Armlength km, Doppler redshift 9 m/s, 0 orbit drift km 0 breathing angle

46 Breathing angle: Trailing angle: θ1 θ2 θ θ

47 Orbit drift: Doppler shift generated by orbit drift: 3.06 x 106 L v L v 23 L 31 v

48 Trailing angle (θ=24 0 ) θ drift in orbit: Redshift generated by orbit drift: x 106 L L 23 L 31 4 v 12 v 23 v

49 θ Trailing angle: breathing angle: θ1 θ2 θ

50 Key Technologies Development Laser metrology, laser frequency stability (Institute of Mechanics, Huazhong University, Wuhan Institute of Physics and Mathematics) Gravitational Reference Sensor Capacitance sensing -- Huazhong University, Drag-free control FEEP thruster and DFC Institute of Mechanics, Dong Fang Hong Company

51 Laser metrology (host institute: Institute of Mechanics) + more institutes in future Technical Elements of Laser Metrology for Space Science Missions Optical bench heterodyne interferometry collimation weak-light phase locking Phasemeter phase measurement ultra-stable oscillator (USO) Environment thermal shielding and control Accessory electrical/optical cables Connecters Telescope

52 Ground based Prototype interferometer

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55 Inertial Sensor Development in HUST fiber Torsion Pendulum Sensitive to torque Inertial sensor box frame & TM micro-operation platform turntable Torsion Balance Sensitive to direct force d 0 =152 um Sensitive Direction Require studying more DoFs simultaneously such as coupling. School of Physics, HUST, China

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57 Experiments on frequency locking of Nd:YAG lasers 57

58 Micro-thruster --Institute of mechanics, CAS Field Emission Electric Propulsion (FEEP) Radio Frequency Ion Thrusters (RIT) Mechanism research of FEEP. Select gallium as propellant (Ga-FEEP) Development of Ga-FEEP emitter. Firing operation (8/10 successful ) New emitter validation. Design of µrit. Development of direct thruster stand Complete the experimental prototype of Ga-FEEP & µrit micro-thruster Direct Thrust Measurement. Life test aiming at 5000h FEEP Test Facility Ignition of Ga- FEEP Direct Thruster Stand Design of RIT

59 Journey to the promised land Next phase of the mission study Early structure formation study, EMRI, IMRI Data analysis, numerical relativity Gravity field recovery for geodesy mission Instrument modelling and error analysis Dragfree control loop... Technological developments in space optics, telescope design, inertial sensors, micro-thrusters, dragfree technologies...

60 International Collaboration Completely open!!

61 In our quest for truth, the road stretches endless ahead, seemingly countless study to be made. Yet we continue our search, everywhere, above and beneath. Qu Yuan ( 屈原, BC) Thank you!