Support for LIGO Calibration and Newtonian Noise Suppression by the University of Texas Rio Grande Valley

NSF's LIGO is the world's premier detector of gravitational waves, observing the Universe through gravity rather than light, and allowing us to witness "dark" phenomena (such as black holes) that are undetectable by other astronomical observatories. These observations are revolutionizing our understanding of astrophysics and cosmology. To look farther and more precisely at the Universe with gravitational waves, advances in instrumentation and calibration must be pursued, but extending the scientific reach of LIGO becomes more challenging with every round of improvement. This award supports research to increase the precision of the advanced LIGO detectors. Additionally, this award supports research into Newtonian Noise (local gravitational interference) to improve the sensitivity of the next generation of gravitational wave detectors. The team will train students in STEM areas of research. With the next major, but incremental upgrade, LIGO A#, the mass of the interferometer end mirrors will increase by a factor of 2.5. This will severely limit the capability of the current photon calibrators unless their laser power is scaled up accordingly. This project will design and test a photon calibrator power upgrade and investigate calibration improvements in time for LIGO A#. Improvements will be related to absolute power calibration and low-latency calibration. On the Newtonian Noise side, efforts are concentrated on characterization and mitigation. This project will develop a 3D numerical model to generate realistic predictions of atmospheric Newtonian Noise effects, based on on-site temperature and airflow measurements. Newtonian Noise is expected to be a dominant low-frequency noise source for 3rd generation detectors. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.