NSF Award
2306989
One of the great predictions of Einstein's Theory of Relativity is that light can be bent by massive, astrophysical objects like stars and galaxies. This phenomenon, known as gravitational lensing, can cause relatively nearby objects to appear stretched and distorted, as if seen through the edges of a magnifying glass. By interpreting those distortions, it is possible to figure out the location of matter creating the lensing. Scientists at Drexel University aim to measure the mass distribution of dark matter in the universe by looking at the shapes of approximately 100 million galaxies. Since galaxies that are near one another also experience similar distortions, the true location and distribution of dark matter can be inferred. Scientifically, this work has a broad impact as it deals with the most fundamental questions of how matter evolves on small scales. As part of this project, the team will also develop a Cosmology Summer School aimed at Philadelphia high school students.<br/><br/>This work involves the first measurement of Cosmic Flexion from large-scale structure, well into the poorly constrained, nonlinear regime, using the Dark Energy Survey (DES). This approach is modeled on cosmic shear measurements in which the lensing signals of pairs of galaxies are correlated. Gravitational flexion (the ``arciness'' of an image) is equal to the gradient of the dark matter density field and is particularly sensitive to small scale perturbations. Cosmic shear measures structure on scales from 2 arcminutes up to several degrees. By comparison, cosmic flexion analysis of large-scale structure can produce constraints on the nonlinear power spectrum from 2 to 20 arcseconds, corresponding to the tens of kilosparsecs scale. The team will also measure flexion-shear correlation functions, which will produce signals ranging from several arcseconds to 10 arcminutes, bridging the gap between the two regimes of cosmic shear and flexion. Finally, the same dataset and reduction can and will be applied to estimate individual galaxy-galaxy lensing signals and produce constraints on galaxy mass functions.The research team will utilize their expertise to develop tools which can be used by the broader community, in addition to providing direct estimates of small-scale cosmic structure.<br/><br/>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.
