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The LIGO Project ( L aser I nterferometer G ravitational-Wave O bservatory )

The LIGO Project ( L aser I nterferometer G ravitational-Wave O bservatory ). Rick Savage – Scientist LIGO Hanford Observatory. New kind of astronomical observatory. Looking for Gravitational waves , not Electromagnetic waves. General relativity – gravitational waves.

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The LIGO Project ( L aser I nterferometer G ravitational-Wave O bservatory )

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  1. The LIGO Project(Laser Interferometer Gravitational-Wave Observatory) Rick Savage – ScientistLIGO Hanford Observatory

  2. New kind of astronomical observatory • Looking for Gravitational waves, not Electromagnetic waves

  3. General relativity – gravitational waves “Matter tells spacetime how to curve.Spacetime tells matter how to move.”J. A Wheeler Albert Einstein1916 GW: oscillating quadrupolar strain in spacetime Laser Interferometer

  4. LIGO: Laser Interferometer Gravitational-wave Observatory Hanford, WA MIT 3002 km (L/c = 10 ms) Caltech • Managed and operated by Caltech & MIT with funding from NSF • Goal: Direct observation ofgravitational waves • Open a new observationalwindow on the Universe Livingston, LA

  5. Movie http://www.einsteinsmessengers.org/

  6. Detection of gravitational waves Michelson interferometer - differential length change sensor

  7. LIGO detectors Power recycled Michelson interferometer with Fabry-Perot arm cavities 4 km-longFabry-Perotarm cavity recycling mirror test masses Laser beam splitter signal

  8. The Challenge for LIGO • Even the most energetic sourceswill generate oscillating length changes in LIGOof about ~10-18 meters i.e. 0.000000000000000001 meters

  9. One meter, about 40 inches Human hair, about 100 microns Wavelength of light, about 1 micron Atomic diameter, 10-10 meter Nuclear diameter, 10-15 meter LIGO sensitivity, 10-18 meter How Small is 10-18 Meter?

  10. H1 detector sensitivity – July 10, 2010 10-19 meters S6 science run – July 2009 to October 2010

  11. H1 detector range – July 10, 2010 1 Mpc = 1 million parsecs 1 parsec ~ 3 light years Sketch: Kip Thorne

  12. One year = 365 x 24 x 60 x 60 = 31,536,000 seconds How Far is 20 MegaParsecs? One parsec = 3.26256 light years Speed of light is 300,000,000 meters/second 20 parsec x 3.26256 LY/parsec x 31,536,000 seconds/ LY x 300,000,000 meters/ sec = 617,328,552,960,000,000 meters LIGO trying to sense motions of 0.0000000000000000001 meters caused by cosmic events 600,000,000,000,000,000 meters away (36 orders of magnitude in distance)

  13. What have we learned so far? • No detections - data still being analyzed • Astrophysical results – upper limits • “If LIGO didn’t see 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.”(Caltech press release) • Gamma ray burst GRB070201 – LIGO “results give an independent wayto reject hypothesis of a compact binaryprogenitor in M31”(Isabel Leonor for the LIGO Scientific Collaboration)

  14. What’s next? Advanced LIGO • Quantum noise limited interferometer • Factor of 10 increase in sensitivity • Factor of 1000 increase in event rate

  15. Laser source: 10 W to 200 W Diode-pumpedYAG lasers

  16. Vibration isolation: passive to active • Masses anddamped springs • Geophones and accelerometers on payload • Active feedback control – 6 deg. of freedom

  17. Test mass suspensions • Single pendulum • Quadruple pendulumwith reaction masses • 40 kg test masses

  18. Advanced LIGO ~2014 Searching (listening) for gravitational waves from cosmic events located 10 times farther away (~500 million light years) Hubble telescope WFPC2 image (NASA - JPL)

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