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Science Opportunities for Australia

Advanced LIGO

Barry BarishDirector, LIGO

Canberra, Australia16-Sept-03

LIGO-G030506-00-M

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Astrophysical Sourcessignatures

Compact binary inspiral: “chirps”» NS-NS waveforms are well described» BH-BH need better waveforms » search technique: matched templates

Supernovae / GRBs: “bursts” » burst signals in coincidence with signals in

electromagnetic radiation » prompt alarm (~ one hour) with neutrino

detectors

Pulsars in our galaxy: “periodic”» search for observed neutron stars

(frequency, doppler shift)» all sky search (computing challenge)» r-modes

Cosmological Signal “stochastic background”

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Early Universe: “correlated noise”

‘Murmurs’ from the Big Bang

Cosmic Microwave

background

WMAP 2003

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International Network on Earth

LIGO

simultaneously detect signal

detection confidence

GEO VirgoTAMA

AIGOlocate the sourcesdecompose the polarization of

gravitational waves

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Detecting a passing wave ….

Free masses

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Detecting a passing wave ….

Interferometer

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Interferometer Concept Laser used to measure

relative lengths of two orthogonal arms

As a wave passes, the arm lengths change in different ways….

…causing the interference

pattern to change at the photodiode

Arms in LIGO are 4km Measure difference in

length to one part in 1021 or 10-18 meters

SuspendedMasses

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How Small is 10-18 Meter?

Wavelength of light ~ 1 micron

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One meter ~ 40 inches

Human hair ~ 100 microns000,10

LIGO sensitivity 10-18 m000,1

Nuclear diameter 10-15 m

000,100

Atomic diameter 10-10 m000,10

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International NetworkLIGO

Hanford Observatory

LivingstonObservatory

Caltech

MIT

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LIGO Livingston Observatory

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LIGO Hanford Observatory

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LIGO Opticsfused silica

Caltech data CSIRO data

Surface uniformity < 1 nm rms Scatter < 50 ppm Absorption < 2 ppm ROC matched < 3% Internal mode Q’s > 2 x 106

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What Limits LIGO Sensitivity? Seismic noise limits low

frequencies

Thermal Noise limits middle frequencies

Quantum nature of light (Shot Noise) limits high frequencies

Technical issues - alignment, electronics, acoustics, etc limit us before we reach these design goals

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Advanced LIGOimproved subsystems

Active Seismic

Multiple Suspensions

Sapphire Optics

Higher Power Laser

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Advanced LIGO

Enhanced Systems• laser• suspension• seismic isolation• test mass Rate

Improvement

~ 104

+narrow band

optical configuration

2007 +

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Advanced LIGOAdvanced LIGOCubic Law for “Cubic Law for “WindowWindow” on the Universe” on the Universe

Initial LIGO

Advanced LIGO

Improve amplitude sensitivity by a factor of 10x…

…number of sources goes up 1000x!

Virgo cluster

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Gravitational Waves A New Window on the

Universe

Advanced LIGO will provide a new way to view the dynamics of the

Universe