Most of humanity's astronomical knowledge has been obtained through electromagnetic radiation. Gravitational waves, one of the most dramatic predictions of Einstein's theory of general relativity, will provide an entirely new way to observe the Universe. This award supports research by the Gravitational-Wave Group at California State University Fullerton (CSUF) contributing to the search for gravitational waves with the Laser Interferometer Gravitational-Wave Observatory (LIGO). The research will focus on i) improving LIGO's sensitivity to transient astronomical events such as black hole collisions and supernovae explosions through a reduction of non-stationary noise in the detector data, and ii) expediting the success of Advanced LIGO by studying the optical properties of samples of its core and auxiliary optics. These projects will have significant student involvement and help train the next generation of physicists. CSUF is a hispanic serving institution. The research activities funded by this award will provide enhanced opportunities to students traditionally underrepresented in scientific research.
Gravitational waves—ripples of warped space and time—promise to provide a revolutionary new way to observe the universe. In this project, researchers at California State University, Fullerton (CSUF) contributed to the search for gravitational waves with the Laser Interferometer Gravitational-wave Observatory (LIGO), through characterization of noise in the LIGO detectors and studies of the light scattering properties of LIGO optics. Supernovae and merging black holes and neutron stars are among the most promising sources of gravitational waves. The gravitational waves from these sources are transient, meaning they are only visible to LIGO detectors for a short time. Searches for transient gravitational-wave signals are limited by transient noise in the detectors that can mimic a real signal. To reduce the negative effects of noise transients, we developed a technique to discard non-astrophysical noise transients by showing that they are statistically related to signals measurements in auxiliary sensors at the detector sites, such as microphones and seismometers, that are not sensitive to gravitational waves. We applied this technique to LIGO's data, improving its sensitivity to transient gravitational-wave signals and identifying sources of transient noise in the detectors. By increasing their sensitivity to gravitational waves, we extended their range, so they can see more distant, fainter gravitational waves. LIGO requires extreme precision to measure gravitational waves, and this pushes the limits of currently available optical technologies (such as mirrors and coatings). Even parts-per-million levels of light scattering from LIGO's optics can degrade its sensitivity to astrophysical gravitational waves. We constructed an imaging scatterometer on the CSUF campus and used it to characterize initial LIGO optics and to evaluate optics for Advanced LIGO. Our results will help improve the range of Advanced LIGO and, in the field of optics, have contributed to our understanding of surface scattering and dielectric thin-film coatings. CSUF is a diverse Hispanic Serving Institution. The activities funded by this award involved undergraduate and master's students, including many students from groups traditionally underrepresented in physics and astronomy, in the cutting edge science of gravitational-wave astronomy. Our group was active in outreach to schools, community colleges, and the public, sharing the results of these projects and the excitement of the coming discovery of gravitational waves.
