Correlating the Gravitational Wave and Electromagnetic Sky Maps

Recent detections of gravitational waves (GWs) from the mergers of binary black hole (BBH), binary neutron star (BNS), and black hole-neutron star (BHNS) systems have initiated the fields of GW and multi-messenger astrophysics. Nearly 100 such systems have been observed to date. Advanced GW detectors are expected to further improve their sensitivities, and to conduct extended observing runs in the next 3-5 years. One of the primary targets of these upcoming runs is the detection of the stochastic gravitational-wave background (SGWB) that arises by summing up GWs from all merging BBH, BNS, and BHNS systems in the universe. This project will promote the study of the SGWB into a new probe of the formation of structure in the universe. It will do so by correlating the SGWB measurements with electromagnetic (EM) observations, such as observations of the galaxy distribution on the sky or gravitational weak lensing. The project will enable strong participation of both undergraduate and graduate students in high-visibility studies in this emerging field, and it will promote participation of women and underrepresented minorities through a series of research and outreach activities and initiatives at the University of Minnesota and more broadly. The project will develop two formalisms to measure correlations of SGWB anisotropy with EM tracers of the large scale structure in the universe. One formalism will build on the existing cross-correlation techniques to measure anisotropy in the GW energy density. The other will leverage existing parameter estimation pipelines for compact binary mergers, hence dramatically (~1000x) increasing the sensitivity to the SGWB due to such mergers. The two formalisms will be applied to the data acquired in the upcoming fourth and fifth observing runs of Advanced LIGO and Advanced Virgo detectors. They will also take advantage of the upcoming Euclid survey that will revolutionize the understanding of the galaxy distribution on the largest scales. Combining these premier data sets, of both GW and EM flavors, with the state-of-the-art analysis pipelines will result in orders-of-magnitude more sensitive SGWB-EM correlation measurements, with a potential to detect such correlations for the first time and start constraining astrophysical and cosmological models. The project will bring together GW astrophysicists and traditional astronomers, and will serve to strengthen the connections between the two communities. Students participating in the project will have unique opportunities to closely work with experts in both GW and traditional astronomy communities, and to play leading roles in defining the emerging new astrophysics and cosmology probes. The project will also bring together experts across the world, specifically from Europe, India, and the United States, hence strengthening the ties across the international scientific community. As the team includes 50% women, a strong effort will be made to promote involvement of women in astrophysics by connecting with appropriate groups and organizations at the University of Minnesota and participating in their activities, meetings, and visits to local schools.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.