Paving the Way for the First Direct Gravitational-Wave Discovery through Improved Noise Budgeting and Detector Characterization

Washington State University, Pullman WA

Investigators

Abstract

The General Theory of Relativity discovered by Einstein tells us that the familiar, everyday force of gravity is a manifestation of something much stranger: the bending of the geometry of space-time by matter. Among the key predictions of the theory, which includes the expanding Universe and the existence of black holes, is the existence of gravitational waves (GW): ripples moving at the speed of light in the geometry of space-time caused by the fast motion of large masses. Although well tested in terms of their indirect effects on binary systems of compact stars, the direct detection of gravitational waves incident on Earth poses an outstanding challenge. The scientific rewards from achieving this ability would be enormous - ranging from probing the extreme dynamics of exploding stars to gleaning information about the state of the Universe almost at the moment of the Big Bang itself. The effort to enable this new window on the universe has occupied several decades of experimental and technological developments that have pushed the boundaries across diverse fields in the physical sciences. The year 2015 will mark a highly-anticipated watershed moment for gravitational-wave physics: The two advanced Laser Interferomenter Gravitational Wave Observatory (aLIGO) detectors will start their initial data taking runs, followed by the commissioning of the advanced Virgo gravitational wave observatory in Europe. The sensitivity of the aLIGO detector will be ramped up to become about ten times better than that of the first-generation detectors, opening up a spatial volume for observing GW sources that will be 1000 times larger than before. This award supports research that helps aLIGO to achieve design sensitivity in the coming years by contributing to a more complete accounting of sources of noise and characterization of the detectors. This will eventually lead to the publishing of GW data to the public with robust data quality flags. Supporting scientific discoveries by empowering the community at large is a primary goal of this project. Additionally, the researchers will continue to engage the faculty of the WSU campuses in Pullman and Tri-Cities to teach undergraduate students about GW science both through lectures and lab exercises. The latter campus caters to a large percentage of Hispanic and Native-American populations, both of which are under-represented, and offers a rare setting for integrating university education with cutting-edge research in gravitation being carried out at a nearby lab. The aLIGO detectors are being commissioned as we speak. These broadband detectors will also target the detection of GWs from multiple sources, such as binary black holes, spinning non-axisymmetric neutron stars, core collapse supernovae, and stochastic GW background of astrophysical or cosmological origins. They will accomplish this by resolving changes in the 4-km separations of its interferometric test mass optics that are a billionth the size of an atom. The WSU team will integrate the multiple new sensors that have been installed in aLIGO into the model of the interferometer noise budget and work on reducing any gap between its prediction and the observed noise floor.