Testing GR with LISA Pathfinder, BBO, and Other Future Projects

Transcription

1 Testing GR with LISA Pathfinder, BBO, and Other Future Projects Bernard Schutz Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Potsdam, Germany (thanks to K Danzmann, J Magueijo) 1

2 Projects LISA Pathfinder: test of MOND LARES: testing frame-dragging to 1% Advanced LIGO/VIRGO/KAGRA: GR strong-field, GW propagation, H 0 to 1%, tightly constrain w. LISA: as above, only better. STE-Quest: currently being studied at ESA Einstein Telescope: 3G GW observatory Big Bang Observer: Measuring the primordial GW background Harvard Sackler Conference B F Schutz: Future Projects 2

3 LISA Pathfinder Testing LISA Technology in Space! Testing MOND at the saddle point (maybe) Harvard Sackler Conference B F Schutz: Future Projects 3

4 LISA Pathfinder Take one LISA link Squeeze it into one spacecraft 4

5 Electrode Housing and Test Mass: LISA Design 5

6 Electrode Housing

7 Chasing Forces on Ground: Trento Torsion Pendulum Test-mass (hollow) Disturbing surroundings (GRS) 7

8 Performance on Ground Uni Trento 8

9 Laser Assembly Flight Model Tests integration into testbed functional tests interface testing control loop actuators noise behavior Harvard Sackler Conference B F Schutz: Future Projects

10 Laser Tests Successful! Laser frequency noise Laser Relative Intensity Noise Harvard Sackler Conference B F Schutz: Future Projects

11 High Stability Monolithic Optical Structures: Same Technology as for LISA Harvard Sackler Conference B F Schutz: Future Projects 11

12 The Local Interferometer: Test-mass to Spacecraft Motion Readout LPF local interferometer has full required LISA performance. 12

13 Test-mass (Spacecraft) Test-mass Link <10 pm/ Hz 13

14 Demonstrated Performance LISA s 10 pm/ Hz Engineering model of the full interferometer system of LISA Pathfinder: Local test mass to spacecraft interferometer Test mass to test mass interferometer 14

15 The Micro-Newton Thrusters Nominal LISA design. Life time test will be partly pending after LPF 15

16 16

17 LISA Pathfinder OMS Flight Hardware Laser Modulator flight unit Phasemeter analogue and digital proto-flight boards Fully Bonded Optical Bench Optical bench construction Harvard Sackler Conference B F Schutz: Future Projects

18 Flight Model Units replace EMs Harvard Sackler Conference B F Schutz: Future Projects

19 The Spacecraft Waiting for a launch in 2014! 19

20 LISA Pathfinder Launcher Baseline launcher: new European VEGA VEGA first qualification launch: Spring of 2012 Successful! LPF: 3rd launch after qualification Backup Rockot launcher maintained in the event of VEGA not being ready Artists impression of VEGA launcher Harvard Sackler Conference B F Schutz: Future Projects VEGA main engine test

21 Launch in 2014 Lagrange Point L1 21

22 Testing MOND (Magueijo & Mozaffari 2012 PRD 85,1) Saddle point: where the Newtonian 1/r 2 accelerations due to the Sun, Earth, Moon null out. If MOND is right, there should still be an acceleration ~ a 0 there. Proposal: not yet agreed by ESA When LPF test program is finished, use thrusters to send LPF from L1 through saddle point: 10 km accuracy expected, position known to 1 km. Transverse Mondian tidal stress time-dependent due to motion of LPF. 22

23 Experimental Expectation Signal and noise for b=50 km offset and 1.5 km/s speed. SNR contours for various offsets and noise levels 23

24 LARES: Frame-Dragging The VEGA qualification launch took the LARES S/C (ASI) into exactly its preferred orbit. Passive satellite: geodesic motion determined by laser ranging from Earth. (Compare talk by Tom Murphy.) Follow-on from Ciufolini et al study of LAGEOS, which measured GR spin-orbit coupling to ~±10%. (Talk by Will.) NB: Requires good Earth model, provided by GRACE mission. 24

25 LARES Accuracy Ciufolini claims that LARES will improve LAGEOS accuracy to ±1%. Iorio disputes this. GRACE mission ends GRACE follow-on planned, will carry extra LPF laser-ranging package for greater accuracy of tidal measurement. Potsdam potato (GFZ) 25

26 Adv. LIGO(3)-VIRGO-KAGRA Binary systems offer clean tests of GR: simple model. NS-NS binaries: 40 yr -1 climbing to 1000 yr -1 by (using network & squeezing -- already implemented in GEO600). [Talks by Nissanke, Mandel, Cadonati.] Detection threshold SNR ~ 12 (total coherent SNR). Loudest event among N will have SNR ~ 12 N 1/3 N = 40: SNR max ~ 40 N = 1000: SNR max ~ 120 δd L /D L ~ 1/SNR With an afterglow, just one event could give H 0 to ±1%, IF detectors have 1% accurate calibration! Hu 2005: The single most important complement to the CMB for measuring the dark energy equation of state at z ~ 0.5 is a determination of the Hubble constant to better than a few percent. GW NS-NS observations could test cosmological constant hypothesis (w=-1) to 1% around (Mainly dependent on NS-NS rates.) 26

27 LISA History 1995: ESA Cornerstone 2000: NASA joins as equal partner, LPF approved. 2006: LISA put into Cosmic Visions competition for L : NASA withdraws, descoped NGO proposed 2012: L1 awarded to JUICE, even though SSAC rated NGO science highest. LISA must wait for L2 selection LISA Science: mhz GWs BH masses solar WD binaries, P orb < 3 hr Very high SNR (up to 10 4 ) Large numbers of sources Low-z BH-BH mergers (talks by Pretorius, Campanelli, Phinney) BH-BH mergers to z > 20 if they happen! Trace structure formation. EMRIs (talk by Yunes) WD-WD: illuminate stellar evolution, SN1a pathway, galactic structure 27

28 LISA: the next few years Waiting for ESA to clarify its policy for L2: Cornerstones? Selection before or after LPF? NASA exercise to examine mission possibilities will report soon. Best scenario: ESA adopts LISA for L2, minor partnership with NASA, launch Meanwhile: must keep science activity on LISA high in both US and Europe! Strong science case is the most important support for selection. 28

29 STE-Quest Under study at ESA for M3. Carries atomic clock, atom interferometer, elliptical orbit. Gravitational redshift: accuracy 10-8, using comparison of Rb clock on S/C with ground stations. Equivalence principle to comparing 85 Rb/ 87 Rb using matter interferometry. Down-selection 2013, final selection 2015, launch

30 Einstein Telescope 30

31 Einstein Telescope Conceptual design study funded by EU ended G technologies: Underground Cryogenic Compensate Newtonian gravity noise 10 km arms Triangular array Proposal waits for first GW detections, operation > 2025 (B Sathyaprakash) 31

32 ET Sensitivity to Binaries (B Sathyaprakash) 32

33 Testing GR with ET ET uses binaries in the same way as AdL and LISA. Many more events than AdL, lower masses than LISA. Polarization; speed of GWs: (c-v)/c ~ No-hair theorem, cosmic censorship. Proof of horizon: observing quasi-normal modes. Nonlinear gravity: observation of tails Cosmic expansion: look for anisotropies in H 0 Primordial GW background down to Ω gw = Even tighter constraints on 1+w, measurements of w a + Astrophysics: gamma-bursts, structure formation, SNe to 5 Mpc, NS EOS and physics, 33

34 BBO Concept study requested by NASA 2005, led by S Phinney. Aim: sufficient sensitivity to measure GW background from standard slow-roll inflation. BBO (Phinney) 34

35 Primordial Stochastic Spectrum Pulsar timing Or none: Ekpyrotic Universe Astrophysical foreground fog? Randall et al (2007) OR: EW phase trans (Nicolis 2003) (LSC-V, Nature, 2009, 460, 990) BBO:

36 BBO Design 36