Illuminating Galaxy Formation with the Atacama Cosmology Telescope

A central goal of extragalactic astrophysics and cosmology is to find answers to questions like: How do galaxies affect their environments? What processes are responsible for shutting off star formation in galaxies? To answer these questions, this research will use a new technique to probe the ionized gas distribution in and around galaxies identified in the NSF-funded Advanced Atacama Cosmology Telescope survey and the Dark Energy Survey, resulting in an improvement of nearly two orders of magnitude over current knowledge. This will set the stage for a further significant increase in sensitivity to follow from the Simons Observatory and the NSF-funded Vera Rubin Observatory, both coming online in the early 2020s. As part of this investigation, the PI will mentor a student from the Columbia University Bridge Program, a two-year post-baccalaureate program that increases the participation of students from under-represented groups in STEM Ph.D. programs, and a summer undergraduate student through the Simons-NSBP Scholars Program, a partnership between the Simons Observatory and the National Society of Black Physicists.

After several 3 to 4-sigma detections in the past decade, measurements of the kinematic Sunyaev-Zel'dovich (kSZ) signal are now set to dramatically improve in precision as a result of the NSF-funded Advanced Atacama Cosmology Telescope (ACT) survey and its overlap with large-scale galaxy surveys, particularly the Dark Energy Survey (DES). This project will develop the 'projected-field' kSZ estimator, building on the PI's recent first detection using this tool. Crucially, unlike other kSZ estimators, this approach does not require a spectroscopic redshift for each galaxy. Application of this estimator to data from ACT and DES to measure the projected-field kSZ-galaxy cross-correlation will result in ~60-sigma measurements of this quantity using data already in hand from these surveys.

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.