Collaborative Research: Preparing for Cosmic Explorer Site Selection

NSF's Laser Interferometer Gravitational-Wave Observatory (LIGO) and its international partners Virgo and KAGRA have opened a new window on the universe by observing hundreds of binary black hole and neutron star mergers. Cosmic Explorer, the United States’ next-generation gravitational-wave observatory, will scale up the proven LIGO technology from 4 km to 40 km detector arm lengths, extending the reach of gravitational-wave astronomy to the edge of the observable universe. Cosmic Explorer will peer deeply into the universe’s dark side—observing gravitational waves from remnants of the first stars, the nature of the most extreme matter, and the most strongly warped spacetime—and will open a wide discovery aperture to the novel and unknown. In parallel to Cosmic Explorer’s technical design, a collaborative, NSF-funded effort established criteria to identify—and has begun to evaluate—potential sites for Cosmic Explorer. This project will take the Cosmic Explorer site evaluation from national to local and site level and from a “long list” of 40 national locations to a “short list” of 6 vetted locations, resulting in a report of sufficient detail to drive a site selection process for Cosmic Explorer led by the NSF. This project will maximize the benefit of the US’s investments in Cosmic Explorer by matching the facility with a location and host community where the project and its participants will thrive. The project will attract and involve students and postdoctoral associates in multi-disciplinary research and will train future leaders in the US’s STEM workforce. This work will directly enable discoveries by CE that will greatly advance science, inspire generations of students, and capture the public’s imagination. We will evaluate the most promising locations for Cosmic Explorer to achieve its science goals, be built within cost boundaries, attract and retain its workforce, and operate synergistically with host communities. To do this we will i) build on the National Suitability Analysis, conducted with Geographic Information Systems (GIS) and public data, to carry out a finer-grained local analysis of promising locations; ii) evaluate the “science per cost” of building Cosmic Explorer at promising locations—in conjunction with the suitability analysis—and more accurately calibrating costs into U.S. dollars; iii) carry out on-the-ground technical assessment of seismicity, geology, and environmental noise; and iv) identify and develop synergies with potential host communities. Results from these areas will inform a down-selection to a “short list” of 6 locations and a report to the NSF. The results of this research will enable a well-informed decision to be made on the most suitable sites for Cosmic Explorer and advance knowledge on the techniques of siting very large, very sensitive instruments in the United States. 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.