The
LIGO Project and the LIGO Scientific Collaboration
What is LIGO?
LIGO, one of the largest projects ever undertaken by the National Science Foundation, has as its goal the detection and study of gravitational waves from large-scale astrophysical sources. Gravitational waves were predicted by Einstein almost 90 years ago but never been observed directly despite a number of experiments over the last 40 years. While strong indirect evidence comes from long-term precision measurements of the periastron shift of binary neutron star system PSR 1913 + 16, it is only with the construction of large-scale high precision interferometers that direct detection of gravitational waves is possible.
LIGO, one of the largest projects ever undertaken by the National Science Foundation, has as its goal the detection and study of gravitational waves from large-scale astrophysical sources. Gravitational waves were predicted by Einstein almost 90 years ago but never been observed directly despite a number of experiments over the last 40 years. While strong indirect evidence comes from long-term precision measurements of the periastron shift of binary neutron star system PSR 1913 + 16, it is only with the construction of large-scale high precision interferometers that direct detection of gravitational waves is possible.
Configuration
LIGO consists of three separate interferometers, two located in Hanford, WA (one 4 kilometers long and one 2 kilometers long) and one in Livingston, LA (4 kilometers long). GEO's 600 meter interferometer is located in Hannover, Germany. In LIGO, the traditional Michelson interferometer is enhanced by placing Fabry-Perot cavities in the interferometer arms, effectively amplifying its length and increasing the accumulated gravitational wave phase shift. A 'power-recycling' mirror located in between the laser and the beamsplitter coherently recirculates laser light back into the interferometer for improved shot noise sensitivity. In addition, a variety of state-of-the-art technologies are used for minimizing spurious noise sources. Frequency, amplitude, and spatially-stabilized 8 Watt Nd:YAG lasers, 25 centimeter aperture l/1000 fused silica low loss supermirrors, advanced seismic isolation systems, precise length and alignment sensing and control systems as well as one of the world's largest high-vacuum system are employed in LIGO.
LIGO consists of three separate interferometers, two located in Hanford, WA (one 4 kilometers long and one 2 kilometers long) and one in Livingston, LA (4 kilometers long). GEO's 600 meter interferometer is located in Hannover, Germany. In LIGO, the traditional Michelson interferometer is enhanced by placing Fabry-Perot cavities in the interferometer arms, effectively amplifying its length and increasing the accumulated gravitational wave phase shift. A 'power-recycling' mirror located in between the laser and the beamsplitter coherently recirculates laser light back into the interferometer for improved shot noise sensitivity. In addition, a variety of state-of-the-art technologies are used for minimizing spurious noise sources. Frequency, amplitude, and spatially-stabilized 8 Watt Nd:YAG lasers, 25 centimeter aperture l/1000 fused silica low loss supermirrors, advanced seismic isolation systems, precise length and alignment sensing and control systems as well as one of the world's largest high-vacuum system are employed in LIGO.
UF and LIGO
UF is a charter member of the LSC and has and has a wide ranging research program dedicated to gravitational wave astrophysics. Among our activities are:
Large Scale Detector Development: Data Analysis
Detector Characterization:
UF is a charter member of the LSC and has and has a wide ranging research program dedicated to gravitational wave astrophysics. Among our activities are:
Large Scale Detector Development: Data Analysis
Detector Characterization:
- DMT Development
- Evanescent Cooling of the Test Masses
- High Power Optics
What is a gravitational wave/radiation?
Gravitational waves are miniscule strains applied to space-time by motion of massive astrophysical objects possessing time-dependent quadropole mass moments. A passing gravitational wave will differentially expand and contract the distance between two mirrors ('test masses') in the arms of an interferometer. Direct observation of gravitational waves presents a formidable challenge, because the magnitude of the dynamic strain is expected to be less than 10-22 near 100 Hz. The astrophysical motivation for detecting gravitational waves is compelling. Unlike the visible sky, the gravitational wave 'sky' is completely unexplored. The LIGO and GEO600 detectors have the sensitivity to observe gravitational waves not only in our own galaxy, but in neighboring galaxies, thus opening an absolutely unique window into these phenomena. Observations of pulsar gravitational waves will allow us to probe their hydrodynamics and ellipticities. Gravitational wave 'bursts' from supernovae and gamma ray bursts can provide direct information about these cataclysmic processes. Mergers of neutron stars and black holes give insight into strong-field gravity and provide a unique experimental test of general relativity. Remnant stochastic gravitational radiation will permit us to look at the universe in the first seconds after the Big Bang.
Gravitational waves are miniscule strains applied to space-time by motion of massive astrophysical objects possessing time-dependent quadropole mass moments. A passing gravitational wave will differentially expand and contract the distance between two mirrors ('test masses') in the arms of an interferometer. Direct observation of gravitational waves presents a formidable challenge, because the magnitude of the dynamic strain is expected to be less than 10-22 near 100 Hz. The astrophysical motivation for detecting gravitational waves is compelling. Unlike the visible sky, the gravitational wave 'sky' is completely unexplored. The LIGO and GEO600 detectors have the sensitivity to observe gravitational waves not only in our own galaxy, but in neighboring galaxies, thus opening an absolutely unique window into these phenomena. Observations of pulsar gravitational waves will allow us to probe their hydrodynamics and ellipticities. Gravitational wave 'bursts' from supernovae and gamma ray bursts can provide direct information about these cataclysmic processes. Mergers of neutron stars and black holes give insight into strong-field gravity and provide a unique experimental test of general relativity. Remnant stochastic gravitational radiation will permit us to look at the universe in the first seconds after the Big Bang.
How you can help...
You can donate your spare CPU cycles to search for gravitational waves from known pulsars in our galaxy! Check out the Einstein @ Home project.
You can donate your spare CPU cycles to search for gravitational waves from known pulsars in our galaxy! Check out the Einstein @ Home project.