Spring 2025 “Meet Yourself” Event

Featuring UArizona Grad Students

3:30 – 4:30pm

Kuiper Space Sciences Building, Room 308

With refreshments served in the 3^rd Floor Atrium at 3:00 pm

Line-up:

1. Vikram Manikantan, Astronomy – “Coincident Multi-messenger Bursts from Eccentric Supermassive Binary Black Holes”
2.  Tyler Reese, Planetary Sciences – “Monte Carlo Modeling of Charged Particle Acceleration across Collision-less Shocks”
3. Ian Matheson, Planetary Sciences – “The Mean Pole of the Hilda Asteroids”
4. Niranjana Shankarappa, Physics – “Estimation of Solar Wind Heating via Turbulent Cascade Models”
5. Sóley Hyman, Astronomy – “Probing the Role of Chaos in Galaxy Evolution with PECCARY”
6. Morifumi Mizuno, Physics – “Plasma Flow in Force-free Magnetospheres:  Two-fluid Model Near Pulsars and Black Holes”

Yu-Dai Tsai, Los Alamos National Laboratory

Dr. Tsai is a Director’s Fellow at the Los Alamos National Laboratory. He received his PhD at Cornell University and was a postdoc at Fermilab and the University of California, Irvine. Dr. Tsai’s research sits at the intersection of particle physics, astroparticle physics, and cosmology, developing theories, searches, and small-scale experiments to probe fundamental laws of physics. He currently focuses on exploring the Elusive Universe, consisting of dark matter, neutrinos, and gravity, studying their signatures in neutrino experiments, space missions, and quantum sensors. Several of his small-scale experiments and search concepts are being implemented in national laboratories worldwide. One of the ultimate goals of Dr. Tsai is to detect dark matter pure gravitationally in the solar system.

Relevant Links:

• https://www.lanl.gov/media/publications/connections/2024-nov/asteroid-data-physics
• https://www.scientificamerican.com/article/dark-matter-black-holes-could-fly-through-the-solar-system-once-a-decade/
• https://www.newscientist.com/article/mg26435190-100-we-may-be-about-to-solve-the-greatest-riddle-of-electromagnetism/
• https://www.symmetrymagazine.org/article/is-dark-matter-the-most-powerful-wave-in-the-universe?language_content_entity=und
• https://www.symmetrymagazine.org/article/a-different-way-of-thinking?language_content_entity=und
• https://www.vice.com/en/article/scientists-want-to-use-asteroids-to-search-for-hidden-fifth-force/
• https://www.youtube.com/watch?v=obDULOzmZ6A

Eonho Chang, University of Arizona

2025 Graduate Student Research Prize Awardee

3:30 – 4:30 pm in Kuiper Space Sciences Building, Room 312

Refreshments at 3:00 pm in the 3rd Floor Atrium

Title: “Halfway to Rayleigh” and Other Insights into the Rossby Wave Instability

Abstract:  The Rossby wave instability (RWI) is the fundamental nonaxisymmetric radial shear instability in disks. The RWI can facilitate disk accretion, set the shape of planetary gaps, and produce large vortices. It arises from density and/or temperature features, such as radial gaps, bumps, or steps. A general, sufficient condition to trigger the RWI is lacking, which we address by studying the linear RWI in a suite of simplified models, including incompressible and compressible shearing sheets and global, cylindrical disks. We focus on enthalpy amplitude and width as the fundamental properties of disk features with various shapes. We find analytic results for the RWI boundary and growth rates across a wide parameter space, in some cases with exact derivations and in others as a description of numerical results. Features wider than a scale height generally become unstable about halfway to Rayleigh instability, i.e., when the squared epicyclic frequency is about half the Keplerian value, reinforcing our previous finding. RWI growth rates approximately scale as enthalpy amplitude to the 1/3 power, with a weak dependence on width, across much of the parameter space. Global disk curvature affects wide planetary gaps, making the outer gap edge more susceptible to the RWI. Our simplified models are barotropic and height integrated, but the main results should carry over to more complex and realistic scenarios.

Unified Astronomy Thesaurus concepts: Hydrodynamics (1963); Astrophysical fluid dynamics (101); Planet formation (1241); Protoplanetary disks (1300)

Bio: I’m a fifth year PhD student in Applied Mathematics working with Prof. Andrew Youdin. My research focuses on hydrodynamic instabilities in protoplanetary disks. In particular, I investigate the role of the Rossby Wave Instability in disk evolution and planet formation through theoretical models and numerical simulations. I’m also interested in applying advanced mathematical techniques to these problems and have worked with machine learning methods in dust-gas dynamics. I completed my Bachelor’s in Astrophysics and Master’s in Scientific Computing and Applied Mathematics at UC Santa Cruz.

W.L. Kimmy Wu, SLAC National Accelerator Laboratory

3:30 – 4:30 pm in Kuiper Space Sciences Building, Room 312

Refreshments served at 3:00 pm in the 3rd Floor Atrium

Title:  Testing inflation and the standard cosmological model with the cosmic microwave background

Abstract:  Inflation–the leading model for the earliest moments of the time, in which the Universe undergoes a period of rapid, accelerating expansion — generically predicts a background of primordial gravitational waves, which generate a B-mode component in the polarization of the cosmic microwave background (CMB). The measurement of such a B-mode signature would lend significant support to the paradigm of inflation. However, observed B modes also contain a component from the gravitational lensing of primordial E modes, which can obscure the measurement of the primordial B modes. We reduce the uncertainties in the B-mode measurement contributed from this lensing component by a technique called ‘delensing.’ In this talk, I will show results of the first and only analysis that reduces cosmological parameter uncertainty, in this case the uncertainty on the tensor-to-scalar ratio from the BICEP/Keck experiments, with delensing.

For upcoming analyses, efficient delensing relies on high signal-to-noise measurements of the CMB lensing mass map. Such lensing maps not only will be essential for testing inflation, they will also provide new cosmological information compared to the primary CMB. This is particularly interesting in light of the current tensions between inferred parameter values of the standard cosmological model LCDM such as the Hubble parameter using different data sets. I will show the latest state-of-the-art measurement of CMB lensing using data from the South Pole Telescope, its cosmological parameter constraints, and discuss implications for cosmic tensions and the sum of neutrino masses.

Bio: Kimmy Wu is an observational cosmology specializing the cosmic microwave background. She is interested in using CMB and large-scale structure data to probe inflation, test the standard model of cosmology LCDM. and find new physics. She completed her undergraduate studies at the University of Michigan at Ann Arbor, did her PhD at Stanford University, and postdoc-ed at UC Berkeley and UChicago before joining SLAC as a Panofsky Fellow.

Monday April 21, 2025

3:30 – 4:30 pm in Kuiper Space Sciences Building, Room 312

The TIMESTEP Research Apprenticeship poster session will be held in conjunction with the Colloquium:

• 3:00 – 3:30 Refreshments and TIMESTEP poster session- 3rd floor atrium of the Kuiper Space Sciences Building
• 3:30 – 4:30 TAP colloquium with Dr. Edwin Kite, University of Chicago, presenting research on “A Case for Mars Terraforming Research”- Room 312 of Kuiper
• 4:30 – 5:00 TIMESTEP poster session continued

Title:  A Case for Mars Terraforming Research

Abstract:  Diverse perspectives inform research on planetary environmental modification. Building on pioneering work by Carl Sagan, we now understand Mars as a world that once sustained rivers and lakes before experiencing global cooling – presenting unique opportunities for understanding planetary habitability changes. Some argue that a hospitable Mars could enable greater self-sufficiency compared to isolated outposts. Others are motivated by the scientific desire to learn about the universe, as the realization of humanity’s dreams to explore the universe is assisted by expanded human presence. While some advocate preserving Mars in its current state, research can transform abstract debates into concrete technical assessments. A key scientific challenge in making Mars’s surface suitable for Earth-like life is understanding planetary temperature modification. Recent advances in engineered-aerosol warming approaches (e.g. Ansari et al. Science Advances 2024) demonstrate unprecedented mass-efficiency (>5000x compared to traditional methods), opening new possibilities for stepwise research into planetary temperature modification. I will discuss what we know about Mars, what we think we know about Mars terraforming (including alternative approaches), and suggest priorities for future research. As we evaluate approaches ranging from minimal intervention to more extensive modification, we must rigorously assess technical requirements, resource efficiency, and risk management. While full planetary environmental enhancement would span multiple centuries, immediate research priorities can focus on understanding fundamental physical, chemical and biological constraints that will shape any future decisions about Mars.

Bio: Edwin Kite is a Resident at Astera Institute in Emeryville, CA, an associate professor with tenure at the University of Chicago, and a participating scientist on the Mars “Curiosity” rover.  Following undergraduate work at the University of Cambridge, Kite moved to UC Berkeley for a PhD in the Earth and Planetary Science Department. Prior to joining the University of Chicago, Kite held prize postdoctoral fellowships at Caltech and at Princeton. Kite is a co-recipient of the Newcomb Cleveland Prize and a recipient of the AGU Greeley Early Career Award. Kite’s research interests include Early Mars, small-radius exoplanets, and Mars terraforming.

Links to articles:

Engineered dust could help make Mars habitable

Terraforming Mars could be easier than scientists thought