Collaborative Research: Cosmic Shear on Extremely Large Scales with the Dark Energy Camera

Dark matter and dark energy make up 95% of the Universe, yet the physics governing these components is not well understood. Weak lensing, the bending of light as it passes by mass in the Universe, is one of the most powerful tools for studying dark matter and dark energy. Weak lensing measurements from the recent Universe have been found to be discrepant with cosmic microwave background measurements from the early Universe, which may indicate that our understanding of cosmology is incomplete.

The investigators will assemble an independent weak lensing data set using public observations covering a new area of sky comparable to the largest state-of-the-art weak lensing surveys. These data will be used to perform an independent analysis and directly address the tension between measurements of the Universe at early and recent times. This program will be part of the education for a diverse group of students.

It will also include outreach efforts that share cosmology with the public by combining art and science in collaboration with Adler Planetarium and the Space Explorers program.

The investigators will use public data from the Dark Energy Camera (DECam) at the NSF’s Cerro Tololo Inter-American Observatory to generate a new weak lensing shear catalog containing approximately 80 million galaxies. This new catalog will be used to perform an independent cosmic shear analysis, which connects weak lensing measurements to cosmological model parameters.

The dataset will cover 5,000 sq. deg. of sky outside of the footprint of the Dark Energy Survey (DES). This investigation will provide a statistically independent cross-check of recent cosmic shear analyses from DES and other surveys. Furthermore, when combined with DES, this program will provide a shear catalog that covers 10,000 sq. deg. of sky, giving access to cosmological scales that have not been explored by current weak lensing surveys.

The public release of processed DECam data will increase scientific accessibility for amateur and professional astronomers. In particular, it will help the community prepare for early data from the NSF-funded Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST).

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.