Searching for gravitational waves with lasers (LIGO)

Searching for gravitational waves with lasers (LIGO)

Rick SavageCaltech

LIGO Hanford Observatory - Richland, WA

UCLA Symposium F2C@80 Nov. 2009

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Transferred to UCLA in Physics in 1974 Jan 1975

» Started working for F. Chen and N. Luhmann as undergraduate lab assistant (with Doug Cook)

– Alain Semet, John Turcek, Steve Obenschain, Jim Holt, Mark Herbst, et al.

1976-1986 Plasma diagnostics» N. Luhmann, T. Peebles, H. Fetterman, et al.

– Microtorr, macrotorr, UT FRC, FIR lasers, CO2 lasers

1986 – 1992 Laser / Plasma interactions » Graduate school in EE at UCLA – Chan Joshi» Masters thesis – Degenerate four-wave mixing in heated CO2 gas» PhD thesis – Frequency upshifting of electromagnetic radiation via an

underdense relativistic ionization front 1992 – present

» LIGO project – Caltech until 1997 then LIGO Hanford Observatory in Richland, WA

Black holes and time warps

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http://www.einsteinsmessengers.org/

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

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LIGO Scientific Collaboration

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General relativity – gravitational waves

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

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Detection of graviational waves


Michelson interferometer- differential length change sensor

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Pulsar System PSR 1913 + 16 (R.A. Hulse, J.H. Taylor Jr, 1975)

Orbit will continue to decay over the next ~300 million years, until coalescence

Gravitational wave emission will be strongest near the end

(Weisberg, Taylor)

Do they exist? Indirect evidence


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Capturing the waveform


Sketch:Kip Thorne

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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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Ligo detectors

Laser

4 km-long Fabry-Perotarm cavity

recyclingmirror test masses

beam splitter

Power RecycledMichelsonInterferometerwith Fabry-PerotArm Cavities

signal

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iLigo hardware

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S5 Science Run Nov 2005 – Oct 2007

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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.

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http://www.nasa.gov/

http://www.nasa.gov/


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108 ly

Enhanced LIGO LIGO today

Credit: R.Powell, B.Berger

Adv. LIGO

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10 W to 200 W laser source

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Single to quadruple pendulum


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Passive to active vibration isolation



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Time warps UCLA Laser/Plasma interactions

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LIGO Scientific Collaboration

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Started as a collaboration between Caltech and MIT

Goal: direct observation of gravitational waves Open a new observational window on the Universe


Laser Interferometer Gravitational-wave Observatory

3030 km(±10 ms)

CALTECHPasadena

MITBoston

HANFORDWashington

LIVINGSTONLouisiana

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South-central Washington» Where Columbia, Yakima, and Snake rivers converge

LIGO Hanford Observatory

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Frank’s thinking ….. inflatable kiyak ? ….

LIGO

credit: Google Maps

Doug CookColumbia River

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closer look – more lasers and optics


Documents

Searching for gravitational waves with lasers (LIGO)