Philip Mansfield
Graduate Student, Department of Astronomy and Astrophysics

Location: ERC 416

Scientific Advisor: Andrey V. Kravtsov

Large scale structure, galaxy formation, numerical physics, algorithm design and optimization
Publications: ADS | arXiv
My current research involves identifying and categorizing a subtle feature called the ''splashback radius'' in dark matter halos. This feature shows up in the outer profile of halos and is caused by particles on their first orbit of the halo.

Ph.D. Thesis Defense
Defense date: July 22, 2020
Ph.D. Thesis: "Why Do Dark Matter Halos Die Together? An Intergalactic Murder Mystery"

"Phil Mansfield's thesis research focused on understanding of properties and clustering of dark matter halos forming in the Cold Dark Matter scenario. In particular, during this thesis work Phil has made significant contributions to our knowledge about reliability of measurements of properties of dark matter halos in cosmological N-body simulations and our understanding of the physical origins of the assembly bias of dark matter halos. Phil has also made exemplary efforts in education, outreach, and mentoring high-school and undergraduate students."
- Andrey Kravtsov, Ph.D. advisor

Thesis Abstract: Galaxies live their lives deep within massive invisible clumps of dark matter called "dark matter halos." The overwhelming gravity of dark matter halos cause their growth and evolution to control and dominate the long-term growth of the galaxies within them. This fact has been widely used to compare our largest galaxy surveys against the predictions of our cosmological models. However, this endeavor faces a long-standing theoretical problem: "dying" dark matter halos (halos whose growth has slowed to a trickle over the past few billion years) are preferentially found nearby one another. This means that large-scale environment is strongly connected to the growth and properties of dark matter halos, and likely their galaxies, too. This connection between halo growth and environment is called "assembly bias." Attempts to mitigate the impact of assembly bias on galaxy models have been stymied by the fact that even after 15 years of study it is still unclear why assembly bias occurs. In this thesis defense, I argue for a model which unifies the disparate theoretical camps into a single explanation for galaxy-mass assembly bias. This defense will also touch on my teaching work while at the University of Chicago.

Department Committees
Past Department Committees:
  • Undergraduate Committee: 2015 - 2016