Searches for Gravitational Wave Transients: Data Analysis for Advanced LIGO and A+ LIGO

This award supports research in relativity and relativistic astrophysics and it addresses the priority areas of NSF's 'Windows on the Universe' Big Idea. Gravitational waves (GW), predicted by Albert Einstein's theory of General Relativity, are the ripples in the fabric of space-time created by relativistic astrophysical systems. Gravitational waves have eluded detection for a hundred years, until 2015, when Advanced LIGO observed GW from two colliding black holes, starting a revolution in the field of multi-messenger astronomy. This detection confirmed a major prediction of General Relativity and opened an unprecedented new window onto the cosmos. Gravitational waves provide a direct probe of complex astrophysical systems. Since 2015, LIGO and its European partner instrument Virgo have reported more than 50 GW events, which are currently under active investigation. Numerous public alerts have been sent to the astronomical community, enabling the multi-messenger observations of those events. In the next few years hundreds of sources are expected to be detected as advanced LIGO reaches its design sensitivity and other instruments join the world-wide network of GW detectors. Even higher detection rates are expected when the LIGO is fully upgraded to its A+ configuration. GW observations will address key research questions including the formation and evolution of black holes and neutron stars, the role of compact objects in the emission of high energy radiation, the properties of nuclear matter, and the nature of gamma-ray-bursts and probe the structure and evolution of the Universe, and, possibly, find physics beyond General Relativity.

These research projects will study some of the most extreme astrophysical events and hold a promise for discoveries of entirely new astrophysical phenomena. Leveraging the extensive experience at UF, the projects outlined here will utilize detection and reconstruction algorithms that use minimal model assumptions and that are capable of detecting GW transients in a wide range of the source parameters, including yet unknown sources. Among the primary detection targets are the recently discovered Intermediate-Mass-Black-Hole (IMBH) objects, hierarchical BBH mergers, and the core-collapse supernovae, which will address a number of open questions in astrophysics. The proposed activities will extend the most promising GW searches for compact binary sources into the binary parameter space not explored yet by existing template-based algorithms. These searches have the potential to study the IMBH sources, constrain the supernovae pair instability mass gap, look inside the galactic nuclei by detecting hierarchical binaries and enable precision tests of General Relativity in the strong field regime by comparing the reconstructed signal waveforms with numerical relativity predictions. Rapid source reconstruction and sky localization will enable joint observations with electromagnetic telescopes and neutrino detectors advancing the field of multi-messenger astronomy. This award also supports the planned upgrade of the baseline data analysis algorithms for the LIGO O4 and O5 runs and increases the scientific potential of the future GW observations.

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.