Probing High-Energy Physics with the Galaxy Bispectrum

This award funds the research activities of Professor Oliver Philcox at Stanford University. Over the next decade, astronomical observatories will measure the positions of tens of millions of galaxies, building three-dimensional maps of the Universe at unprecedented resolution. By combining such datasets with mathematical models, physicists expect to learn about the origins of the cosmos, shedding light on physics at energy scales far above those accessible in the laboratory. Research in this area advances the national interest by promoting the progress of science in one of its most fundamental directions: the discovery and understanding of the laws of nature. In his research, Professor Philcox will develop and apply new tools to search for novel signatures from the early Universe, in particular ``folded non-Gaussianity'', which can be imprinted by energy losses in the first fractions of a second. The research will combine theoretical modeling with numerical analysis, making use of high-performance computing and observational data. This project is also envisioned to have significant broader impacts. Professor Philcox will involve graduate students and postdoctoral researchers in his research, and thereby provide critical training for junior physicists beginning research in this field. He will also give lectures on the research results in both academic and public settings. More technically, Professor Philcox will perform searches for folded non-Gaussianity in the galaxy bispectrum, exploring broad classes of models including energy dissipation during inflation. The research will combine recent advances in high-energy theory, including the open effective field theory of inflation, with state-of-the-art modeling of galaxy clustering using the effective field theory of large-scale structure. Professor Philcox will derive analytic models for the galaxy bispectrum, incorporating both early Universe signatures and late-time gravitational evolution. A key result will be the application to public clustering data from the Dark Energy Spectroscopic Instrument (DESI), providing the first constraints on a well-motivated, but as yet unexplored, class of early Universe models. This approach will be further used to map out new discovery spaces relevant to current and future surveys, including Spec-S5. 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.