Searching for gravitational waves with lasers

Searching for gravitational waves with lasers

Rick SavageCaltech

LIGO Hanford Observatory - Richland, WA

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Sept 1974 - transferred to UCLA in Physics Jan 1975 - started working for F. Chen and N. Luhmann

as undergraduate lab assistant (with Doug Cook) 1976 to1986 - plasma diagnostics with N. Luhmann, T.

Peebles, H. Fetterman, et al. 1986 to 1992 - graduate school in EE at UCLA with

Chan Josh, Warren Mori, Ken Marsh, Chris Clayton, et al.» Masters thesis – Degenerate four-wave mixing in heated CO2 gas» PhD thesis – Frequency upshifting of electromagnetic radiation via an

underdense relativistic ionization front 1992 to present - LIGO project at Caltech until 1997

then LIGO Hanford Observatory in Richland, WA

LIGO-G0901004 UCLA Symposium F2C@80 Nov. 2009

Black holes and time warps

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LIGO: Laser Interferometer Gravitational-wave Observatory

3002 km(L/c = 10 ms)

Caltech

MIT

• Managed and operated by Caltech & MIT with funding from NSF

• Goal: Direct observation ofgravitational waves

•Open an new observationalwindow on the Universe

Livingston, LA

Hanford, WA

LIGO-G0901004

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LIGO Scientific Collaboration

UCLA Symposium F2C@80 Nov. 2009LIGO-G0901004

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General relativity – gravitational waves

UCLA Symposium F2C@80 Nov. 2009

Laser Interferometer

GW: oscillating quadrupolar strain in spacetime

“Matter tells spacetime how to curve.Spacetime tell matter how to move.”

J. A Wheeler

Albert Einstein1916

LIGO-G0901004

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Potential sources

Credit: AEI, CCT, LSU

Coalescing Binary Systems• Neutron stars,

low mass black holes, and NS/BS systems

Credit: Chandra X-ray Observatory

‘Bursts’ galactic asymmetric core collapse supernovae

cosmic strings

???

NASA/WMAP Science Team

Cosmic GW background stochastic, incoherent background

Casey Reed, Penn State

Continuous Sources Spinning neutron stars

probe crustal deformations


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Capturing the waveform


Sketch:Kip Thorne

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Detection of gravitational waves


Michelson interferometer- differential length change sensor

LIGO-G0901004

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Ligo detectors


Laser

4 km-long Fabry-Perotarm cavity

recyclingmirror test masses

beam splitter

Power RecycledMichelsonInterferometerwith Fabry-PerotArm Cavities

signal

LIGO-G0901004

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Beam tubes and chambers


Beam tubes:• 1.2 m diameter• LN2 pumps at ends• P < 1e-09 torr• dominated by H2

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Isolated environment for test masses


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Suspended test masses


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NS-NS binary inspiral range ~ 15 Mpc (S/N = 8)

Initial LIGO displacement sensitivity


Antenna patterns

+pol

Gpol

avg

S5 science runNov. `05toOct `07

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No detections (so far) - data still being analyzed Astrophysical results – upper limits

“If LIGO didn’t detect it, then it can’t be bigger than …”» CRAB pulsar – “no more than 4 percent

of the energy loss of the pulsar is caused by the emission of gravitational waves.” (ApJL 683, L45)

» Gamma ray burst GRB 070201 – LIGO “results give an independent wayto reject hypothesis of a compact binaryprogenitor in M31”(ApJ 2008, 681, 1419)

» Upper limit on the stochastic gravitational wave background(http://www.nature.com/nature/journal/v460/n7258/pdf/nature08278.pdf)


Scientific results of S5 run

Credits for X-ray Image: NASA/CXC/ASU/J. Hester et al.Credits for Optical Image: NASA/HST/ASU/J. Hester et al.

http://www.nasa.gov/

http://www.nasa.gov/

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What’s next? Advanced Ligo.

Quantum noise limited interferometer

Factor of 10 increase in sensitivity

Factor of 1000 increase in event rate


16UCLA Symposium F2C@80 Nov. 2009

Laser source: 10 W to 200 W

LIGO-G0901004

Diode-pumpedYAG lasers

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Vibration isolation: passive to active


• Geophones and accelerometers on payload• Active feedback control – 6 deg. of freedom

• Masses anddamped springs

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Test mass suspensions


• Quadruple pendulumwith reaction masses

• 40 kg test masses

• Single pendulum


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Time warp – 1763 Boelter Hall

LIGO-G0901004


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To Frank ……. thank you.

LIGO-G0901004

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Searching for gravitational waves with lasers