Instrumentation and Simulation for Advanced LIGO Upgrades and Future Gravitational Wave Detectors

This award supports research in relativity and relativistic astrophysics and it addresses the priority areas of NSF's "Windows on the Universe" Big Idea. The impact of the field of gravitational wave detection in recent years is difficult to overstate. Results from the Advanced LIGO detectors have regularly captured the imagination of the public, making headline news while providing vital new data to enable studies at the forefront of scientific knowledge.

Regular detections of binary black hole systems have allowed scientists to compile a catalog of previously unknowable celestial objects. Precise measurements of the gravitational waveforms from the detected events allow us to probe the details of fundamental theories underpinning our understanding of the universe. The work supported by this award is directly aimed at improving the LIGO detector sensitivity in the future, as well as developing technology for and informing the design of the next generation of gravitational wave detectors.

These goals will have a direct payoff in the form of continued discoveries and better science products. The USA has long been recognized as a leader in the field of gravitational wave astronomy. Continued research to push the boundaries of what is possible with gravitational wave detectors is necessary to maintain this position over the next decades.

The majority of the work supported by this award will be performed by graduate students and undergraduate students, providing them with excellent training opportunities to develop their skills, therefore enriching the future American scientific workforce. The subject of the research is also a very fertile ground for outreach to the wider public, which is one of the best ways to broaden participation in science across society.

This award supports both simulation and experimental project components. The simulation component is aimed at characterizing the low frequency (<30Hz) noise of the Advanced LIGO interferometers, and using the knowledge gained to inform the design of future upgrades. Characterizing the low frequency detector noise is very challenging because it is a combination of many individual noise sources, and because even these individual noise sources are cross-coupled and difficult to model and estimate.

However, new simulation tools are being developed that have the capability to untangle these noise contributions, and this project will apply these tools to tackle this problem. The same tools will also be used to support commissioning of the Advanced LIGO detectors in the lead up to the next two observing runs, both of which will include new hardware and configuration upgrades to the interferometers.

The experimental component of this project includes the development of a new method for sensing misalignment and other optical imperfections in laser interferometers, which has some practical advantages over the currently used schemes. Detailed comparisons will be made between the different methods in tabletop laser interferometry experiments, in order to inform design choices for the gravitational wave detectors of the future.

Also supported is a project to experimentally demonstrate the interferometric performance of new beam shapes (higher-order Hermite-Gauss modes), which have the potential to reduce the impact of one of the fundamental noise sources in laser interferometers: thermal noise.

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.