Opening the Gravitational-Wave Band Below 30 Hz for LIGO and Cosmic Explorer

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

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 Advanced LIGO detectors will continue to make discoveries in the upcoming years with the “A+” upgrade. The next two observing runs, O4 and O5, will culminate with the A+ detectors operating at an unprecedented sensitivity. The LIGO Scientific Collaboration is now exploring technologies that can be deployed after O5 (circa 2028) to ensure the next sensitivity leap forward. This award funds work that will improve the sensitivity of current and future gravitational-wave detectors at low frequencies. This work will enable the detection of more and higher-fidelity astrophysical events, and increase access to high-mass black-hole collisions at cosmological distances. The work supported by this award will involve mechanical engineers and physicists, with opportunities for graduate students as well as undergraduate students (via the MIT UROP program) in both of these fields. This ambitious goal can be reached by improving the detector's test mass suspension system to lower its vertical resonance frequency. This approach, coupled with heavier optic mass, can lead to a reduction of seismic, thermal and quantum radiation pressure noises. Several improvements will be considered, including: increasing the suspension length and the stress of the fibers that hold the test mass, and employing lower-noise sensors. These techniques can lead to an improved LIGO suspension system (in current facilities), and will also be applied in the next-generation gravitational-wave detector Cosmic Explorer. The proposed work will couple these two synergistic efforts by developing, together with the LIGO Laboratory, the Cosmic Explorer Project, and the LIGO Scientific Collaboration, a conceptual design for an improved suspension system for LIGO and an early design concept for the Cosmic Explorer suspension. 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.