Searching for missing matter in the Universe using advanced computer simulations and synthetic observations

Silvia Devin W, Boulder CO

Investigators

Abstract

Dr. Devin Silvia is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to carry out a program of research and education at Michigan State University. From the moment the first star ended its life in a catastrophic supernova explosion, elements heavier than hydrogen and helium have been "polluting" the once pristine gas left over from the Big Bang. Understanding the nature of this evolution from a simple universe containing only hydrogen and helium to the one we know today, rich with the elements that have become the building blocks of life, is of great interest to the astrophysics community. However, accurately modeling and understanding this process has proven difficult. The research program to be carried out by Dr. Silvia is aimed at solving one particular mystery: why does some of the matter in the Universe appear to go missing as a function of cosmic time? While observational astronomers have endeavored to locate this matter using the powerful Hubble Space Telescope (HST), much of it continues to elude detection. Dr. Silvia will employ state-of-art cosmological simulations capable of accurately tracking the matter contained in the Universe and calculating its physical properties. By using the results of these simulations to produce synthetic observations that mimic those captured by the HST, Dr. Silvia will be able to answer the question: where is the missing matter is hiding? Alongside this research program, Dr. Silvia is driven to address the apparent lack of diversity within STEM disciplines by developing and teaching a new astronomy course that will leverage innovative educational practices shown to increase learners' identification as members of the STEM community. The course will also serve to provide learners with an enduring understanding of scientific topics and the ability to think critically about observed phenomena. A significant obstacle in understanding the chemical evolution of the intergalactic medium is turning observations of quasar absorption lines into reliable estimates of metal content. In an effort to address this obstacle, the primary objectives of this work will be to characterize the mass content and ionization properties of the intergalactic and circumgalactic media and use the results to interpret current observations and inform future ones. The PI will meet these objectives by carrying out a suite of state-of-the art cosmological simulations that employ a newly-developed chemical network solver, enabling non-equilibrium calculations of the ionization structure of the intergalactic and circumgalactic media. Using completed simulations, the PI will leverage a novel technique for generating synthetic quasar absorption line spectra and compare the results to observations from the Hubble Space Telescope's Cosmic Origins Spectrograph. The PI will then compile a catalog that links spectral features to the physical conditions that generated them. Alongside this research program, the PI plans to design and teach a new course for first year undergraduate students that focuses on topics in astronomy and is built using the elements of inquiry-based learning. Distinct from traditional teaching practices, an inquiry-based approach to teaching and learning can be very effective at creating an enduring understanding of scientific topics and increasing the likelihood that students of all backgrounds identify as members of the STEM community.