LISA Laser Interferometer Space Antenna: The Mission Mike Cruise For the LISA Team

The Gravity Wave Spectrum

The LISA Mission Key Points LISA will detect gravitational waves from known galactic binaries LISA will permit the study of MBH-MBH collisions out to z~10 LISA will provide high accuracy signals (s/n~ 10 4 ) to explore the gravitational potential of Black Holes LISA Will place limits on the graviton mass

The Astronomical Science Binaries-dynamics, strong gravity, populations MBH-BH or MBH-MBH WD-WD Binaries

Binary System Physics “New window on the Universe” – GWs probe regions of the Universe that are unobservable electromagnetically. Gravitational wave observations allow high precision measurements of black hole masses and spins (to < 1%) – provides a survey of astrophysical black holes. Observations of SMBH mergers tell us about the properties of galaxies and the rate of galaxy mergers. Observations of stellar mass black holes tell us about stellar evolution in various environments. GW observations provide a test of General Relativity, e.g., may use EMRI observations to test “no-hair” theorem or to detect exotic supermassive compact objects.

LISA Science

Science : Fundamental Physics Graviton Mass Polarisation state : test of GR Detailed tests of GR in deep BH-BH orbits Search for higher dimensions Tests of string theory Access to electroweak, GUT and Planck scales

The LISA Project

Three Interferometers Path length 5 million km Precision 10 pm Ability to reconfigure interferometer

The Orbit

Basic Principle Two test masses Laser beams Gravitational Wave  l/l ~10 -23, in one year  l~ 10  m/ root Hz For l= m

The proof mass

Proof Mass Enclosure

Laser Properties Laser power of ~ 1 watt delivers watts at 5 million km. A reflected beam would result in arriving back at the generating spacecraft. Laser signal is detected and phase locked to another 1 watt laser for the return journey. Laser noise couples directly into separation noise- 30 Hz/root Hz is too large, unless the arms are exactly equal. Time delay interferometry can simulate equal arms by comparing phases of delayed signals.

Telescope and Optical Bench

Optical Bench Maturing concept – much to be demonstrated !

Time Delay Interferometry Form linear combinations of phase comparisons with signals delayed by the light travel times between s/c 1: Local s/c2 3 Some of these combinations are completely independent of laser noise and test mass motions Other combinations essentially remove the GW signal and leave the instrumental noise

Phase measurement

Drag Free Control Solar particle fluxes The drag free system must limit Acceleration to below ms -2 /root Hz And position to m /root Hz

Proof Mass Charge Control

The LISA Pathfinder Instrument

The First Interferometer 1887 X20 by 2015

Galactic Binaries

Unresolved BH and WD Binaries

Event Rates

LISA Science

Exploring the Gravitational Potential

GW Sources – Cosmological Quantum fluctuations in the early Universe are stretched as the Universe expands – see a “stochastic” background of GWs. These probe back to before1s after the Big Bang.

Cosmological signals Supersymmetric phase transition which is strongly first order generates bubbles which collides giving GW emission. Next to minimal models generate  = Cosmic strings and Goldstone modes – massless scalar modes-  =10 -5 New modes -radion – curvature -Nambu-Goldstone- brane separation

The LISA Project

Key Points LISA is not an incremental mission –It breaks entirely new scientific ground –It benefits from new technology –It will open a new window on the universe LISA is currently a 50:50 joint project between ESA and NASA Launch could be in 2018

Basic Principle

Time Delay Interferometry