1. From the earth to the Stars
After the detecion of Gws on earth, in now time to go the Stars. LISA for (Laser Inteferometer Space Antenna) is a join project ESA/NASA for a new mission. You can regonize a photo of VIRGO and on the top a picture the futur LISA mission LISA consist of 3 spacecraft, each with a Y shaped payload, form an equilateral triangle with sides of 5 millions kms in length. This configuration, where the two branches of each satellites coincide with the branches of the others spacecraft, form one of up to three Michelson-type interferometers.

2. LISA SYMPOSIUM 2006

3. On this simple movie, the trajectories of the 3 spacecraft is shown
On this simple movie, the trajectories of the 3 spacecraft is shown. The centre of the triangular formation of the 3 spacecraft is in ecliptic plane, 1AU from the sun and 20 behind the earth. Simultaneously the plane is inclined at 60 degree with respect to the ecliptic.

4. Orbiting
These particular heliocentric orbits for the 3 satellites were chosen such that the triangular formation is maintained throughout the year with the triangle appearing to rotate about the centre of the formation one per year.
Each satellites is on his own orbit around the Sun.
This allows a single space-based detector to provide directional information on the GWs.

5. LISA Performances Periodic sources burst sources Hulse-Taylor
This figure shown the comparison of frequency range of sources for ground based detector and LISA. The frequency band for VIRGO is approximately the same of LIGO). This two curves correspond of one year of observation.
The frequency band for the ground based detector is essentially limited at frequency below one hertz because on the earth, it exist a background due to the Newtonian gravity gradients
Essentially the two main sources of gravitational sources for LISA are the galactic binaries and the massive black holes expected to exist in the centers of most galaxies.

6. Science Goal LISA frequency band : 10-4-10-1 Hertz
LISA science goal complementary to ground based interferometer
Short-period known galactic binaries
Mergers of massive ( Msun) and intermediate mass ( Msun)
Compact objects (NS, BHs) spiralling into massive and intermediate mass BH
Astrophysical stochastic background : WD-WD galactic and extragalactic
Gravitational wave signals from the early universe
But, because the booths kinds of the detectors (ground-based and space based) have similar energy sensitivies, their different observing frequencies are ideally complementary

7. Massive Black Hole Numerical Post Newtonian relativity Post Newtonian
This is a simple picture of the frequency observed during the inspiral of two Massive Black holes.
The first phase is the inspiral mode where the 2 BHs turn around each other. Normally, LISA can detect the GWs of this phenomena long time ago the coalescence. This type of calculation can be done on the post Newtonian approach.
The second phase, has properly to speak, is the coalescence, at contrary this calculation can be done in numerical general relativity, because we are in presence of strong gravitational field.
This last years, some important progress were made.
The last phase after the coalescence, is the ringdown and calculation in the post Newtonian can be done.
Image of NC6240 taken by Chandra
Showing a butterfly shaped galaxy
Product of two smaller galaxies
(two active giant BH)

8. Massive Black Hole (cont.)
Post Newtonian calculation
One year before coalescence
First day
First day
Last day
This is an example of Post Newtonian calculation of two MBHs of 105 solar masse at 1 Gigaparsec from LISA one year before the merger.
During the first day the frequency of the GW is approximately monochromatic
The frequency evolve little and the strain (h) is in the domain of LISA.
In the last day before coalescence (in the limit of this type of calculation), the frequency and the amplitude change rapidly.

9. Massive Black Hole (cont.)
Relativity :
From inspiraling post-Newtonian waveforms-> precision test of general relativity
From merger waveforms (numerical relativity) -> test of non linear gravity.
Astrophysics :
Cosmic history of MBH’s-MBH’s
3 Gparsec
This simple picture shown the evolution of frequency and amplitude for different couple of BHs.
Events rates : 0.1 to 100 years !

10. Extreme Mass Ratio in Spiral (EMRI)
Small body spiralling into central body of 105 to 107 Msun
This is more complicated problem, the extreme mass ratio in spiral.
It is the case when a little mass is captured by example by a BH.
The prediction of number of events/year is important (recapitulated in the small table here) and depends of the couple. But also the form of the GWs depend strongly of the mass ratio and of the initial condition. The figure show two examples of EMRI with different conditions.
Relativity :
Relativistic orbits
Astrophysics :
Probe astrophysics of dense cluster around MBH’s
Existence and population of IMBH
Events rates :
for 10Msun+106Msun
10-90 for 0.6Msun+ 106Msun
1 for 100Msun+106Msun

12. Some properties of GW
recall has the use of the experimentalist
The wave is transverse, it is perpendicular to its direction
of propagation.
The deformation produced by a wave conserves surfaces.
If the distance between two aligned masses increases, the distance between the two others masses along the perpendicular direction decreases.
The wave is polarized.
H+ and Hx
First point, of course, the GW acts uniquely on mass.
Geometrical interpretation of general relativity. L and ∂L should be interpreted as a propre distance. h is indeed a distance.
Important properties :

13. Indirect proof tP [s] Einstein  prediction
Hulse-Taylor Binary PSR (1974)
Nobel Price (1993)
Remark : Outside of LISA

14. How to measure L≈5106 kms Six free falling “mirors”
Use interferometry for measuring
LISA frequency band : Hertz
L≈5106 kms
The spacecraft mainly serve to shield a « proof masse » (or a mirror). The proof masse sudden just the gravitation.
LISA can be described as a big Michelson interferometer, but the actual implementation in space is very different from a classical interferometer.
In classical interferometer, the light is reflected to the mirror and send back.
The laser light going out from the spacecraft to the other corners is not directly reflected back because the very little intensity would be left over that way.
1 Watt send 0.7 picowatt received.
In fact, each internal laser is phase locked either to is companion, forming the equivalent of a beam splitter or is like an amplifying mirror

15. Free falling (Inertial mass)
Principle
Inertial mass inside the satellite
Inertial mass
satellite
The principle of the inertial masse is summary on this simple animation.
On the top is a schematic view of one satellite. The two branches containing two inertial masses, playing the role of mirrors and two lasers associated with two telescopes.
The mirror made on gold platinum (4 cm in side) inside the satellite is isolated from the satellite. Around each cubes a pair of electrodes measure the displacement of the cube.
Voltmeter

16. Free falling (Inertial mass) cont.
Solar Wind
satellite
Sun
Voltmeter
The resulting motion of the solar wind would be 104 times larger than the tiny motion due to GW

17. Free falling (Inertial mass) cont.
Thrusters
Inertial mass
Solar Wind
satellite
Sun
Voltmeter

18. Free falling (Inertial mass) cont.
Thrusters
Inertial mass
Solar Wind
satellite
Voltmeter

19. Free falling (Inertial mass) cont.
Thrusters
Inertial mass
satellite
Voltmeter

20. Free falling (Inertial mass) cont.

21. Interferometry Diffraction widens the laser beam to many kilometres
0.7 W sent, 70 pW received
Need 6 lasers (NdYag-1064nm)
Michelson with a 3rd arm, Sagnac
Capable to distinguish both polarizations of a GW
Orbital movement provides directionality

22. 2 3 L1 L2 L3 Interferometry cont.
Laser frequency
Response function of Michelson interferometer. 2 3 L1 L2 L3
Time Delay Interferometry

23. Noise Limitation Strain one year integration Frequency
Acceleration noise: m/(s2 Hz)
Quality of drag-free control, Gravity gradient noise
Shot noise : 70 pw
Armlength penalty: 5 Million kilometer
Strain one year integration
Frequency

24. Physical Noise
Galactic Background.

25. Summary Proposed to ESA 1993, approved as a Cornerstone Mission 1996
Collaborative ESA/NASA mission with a 50/50 sharing ratio
ESA: Responsibility for the payload I&T, 50% of the payload (nationally funded)
NASA: 3 S/C, launcher, ground segment (DSN), mission ops
Science ops will be shared
Data analysis by two independent teams (Europe and US)
Launch foreseen in the 2014/??? timeframe

26. Technological mission
LISA Pathfinder
Technological mission
The LISA Technology Package on board of LISA PATHFINDER will enable testing of following
LISA key technologies:
'Inertial Sensor': to demonstrate that the test masses are really flying free of all external influences and to detect changes in the position and orientation of the satellite relative to the proof mass; 'disturbance-free flight control': multiple sets of thrusters at µ-Newton levels (not part of LTP) will be used to control the spacecraft position to a few microns. The thrusters are to counteract the changes in position and orientation of the spacecraft due to external forces in order to keep it centred on the proof mass. This will also include test of the algorithms of the system control.
‘laser interferometer': to measure the absolute position and attitude and the difference in the displacement of the two proof masses to validate that each is 'disturbance-free' within the requirements.

27. LISA Pathfinder
LISA Test Package

28. LISA Pathfinder
where
Launch foreseen in the 2009 timeframe

29. Contribution to the interferometry of LISA Pathfinder.
Team LISA APC
Contribution to the interferometry of LISA Pathfinder.
Development of a simulator for the LISA mission (LISA Code).
R&D in Laser frequency stabilization (Iodine molecular line)

30. End