Mary Precious Feutsop Ngouane
Carleton College
Faculty Advisor: Prof. Kiyoshi Masui
Research Supervisor: Ryan Raikman
Department: Physics
Biography
Mary Precious is a Physics and Computer Science major at Carleton College, whose
research runs from galaxy evolution to cosmology. She uses cosmological simulations to
trace how merging dwarf galaxies shaped the Milky Way, which she has shared at multiple
conferences, including an oral talk at the American Astronomical Society, and is now writing
as the first author. Precious has also worked in experimental optics with light-shaped polymers,
building and characterizing optical instruments and the systems that push their precision.
This summer, as an MSRP researcher at MIT, she is using fast radio bursts to track down the
universe’s missing baryons. Precious is also passionate about making physics inclusive and
accessible. That commitment led to her role as a student ambassador for the American Physical
Society and as an APS Advocacy Champion. She works to advance science policy and broaden
support for physics and its future.
Where are the Missing Baryons?: A Modular Framework for FRB
Cross-Correlation Analyses
Mary Precious Ngouane1, Ryan Raikman2,3 and Kiyoshi Masui2,3
1Department of Physics and Astronomy, Carleton College
2Department of Physics, Massachusetts Institute of Technology
3MIT Kavli Institute for Astrophysics and Space Research
A large fraction of the universe’s ordinary matter resides as diffuse ionized gas that galaxy
surveys cannot detect directly. Fast radio bursts (FRBs), millisecond flashes of radio light
from extragalactic sources, let us probe this gas. Free electrons along each signal’s path delay
its frequencies by a measurable amount, the dispersion measure (DM). Cross correlating FRB
DMs and positions with galaxy maps has recently yielded first constraints on how this gas is
distributed around galaxies. This project consolidates and optimizes the theoretical modeling
for these analyses into an importable package, which takes a description of the universe and
predicts how DM and FRB positions trace galaxies in the sky. Because DM traces the gas
along the line of sight, a stronger small-scale correlation with galaxies means the gas sits in
halos, while a weaker one means feedback has expelled it. Independent code implementations
validate every statistic to percent-level agreement, the fitting code runs five times faster, and
automated tests confirm identical results. To interpret measurements, the framework supports
standard cosmological calculations, extended analytic methods reaching smaller scales, and
simulations that follow gas physics directly. Testing these models against data brings us closer
to where the universe keeps its ordinary matter.
