We are a group of scientists focused on Extreme Plasmas around Compact Objects (EPaCO), driven by one big question:
What does energetic radiation tell us about far-away astrophysical environments, and how can we build reliable digital twins of these extreme systems?
Our work focuses on the plasma physics of black holes, neutron stars, and magnetars. In these environments, multi-scale and multi-physics challenges drive some of the most dramatic events in the universe. We follow two main directions. We treat magnetars as laboratories for strong-field QED, in regimes that no experiment on Earth can reach. We also develop radio transients such as fast radio bursts into probes of the plasma at their source. We start from open questions in observational astronomy and build theoretical and numerical models of the nonlinear plasma dynamics and QED effects that shape these systems. To support this, we co-develop open-source simulation tools such as Entity, designed for performance across scales and for next-generation computing. We also care about how our science is understood and shared, and we make complex ideas accessible through teaching and outreach. We are grateful for support from the National Science Foundation (NSF) and national computing awards. See EPaCO group members.
Our Values
We build science that lasts, and we do it together.
Our group is grounded in the following principles:
- Curiosity first: we are excited about difficult problems and asking hard questions.
- Collaboration and openness: everyone contributes, and everyone learns.
- Lowering the entry barrier: we support newcomers from day one, with an open knowledge base and learning in pairs. No prior computing experience is needed.
- Modeling for impact: we contribute to open-source tools that outlive individual projects and serve the broader community.
- Care and credit: we value honest communication and clearly stated expectations. We agree on credit at the start of every project, and no contribution goes without acknowledgement.
Group Members & Collaborators
Strong-Field QED and Radiative Plasma Flows in Magnetar Magnetospheres
EPaCO team: Dr. Adrien Soudais, Thomas Kornfeld (’28)
Modeling plasma flows and radiative feedback in magnetar magnetospheres using particle-in-cell simulations, with self-consistent strong-field QED effects and direct comparison to X-ray observations from NuSTAR, NICER, and XMM-Newton.
Coherent Radio Wave Generation in Relativistic Plasma Environments
EPaCO team: Shanza Arooj (GR), Logan Eskildsen (’28)
Investigating observationally testable mechanisms for fast radio bursts and other radio transients, such as coherent emission during plasmoid mergers in reconnection, the electron cyclotron maser instability, and mode conversion at relativistic magnetized shocks.
Radio Wave Propagation in Neutron Star Magnetospheres
EPaCO team: Dawei Dai (GR), Alice Gaehring (GR)
Studying how radio waves interact with plasma in neutron star magnetospheres, and how plasma conditions and magnetic geometries shape observable signatures such as polarization and frequency-dependent intensity. This includes analytic theory of mode conversion and ray tracing through magnetospheric plasma.
Global Dynamics of Magnetospheric Structures
EPaCO team: Dr. Adrien Soudais, Ryan Chen (’29), Kayla Reardon (pre-college)
Investigating the large-scale behavior of magnetized plasma around magnetars and black holes. We use force-free electrodynamics and plasma simulations to study energy transfer, the evolution of magnetic structures, and the plasma instabilities that shape high-energy emission and variability.
Jens Mahlmann (Assistant Professor, Dartmouth College): Group lead, coordination, and research facilitation. My work focuses on magnetar magnetospheres, radio transients, and method development. Right now, I am most excited about reading fast radio bursts as messages from the plasma where they are born. Long-term, I aim to develop reliable first-principles models of radiation-rich plasmas. Outside of work, I enjoy skiing, squash, biking, and Hip Hop music. I’m currently obsessed with the art of Natalia Lafourcade, and I love speaking Spanish whenever I can.
If you’re interested in joining the group, please email us a description of your research interests, program goals and a CV with contact information for references to start a conversation.
Teaching & Outreach
- Courses: PHYS 118 Computational Plasma Dynamics, PHYS 115 Magnetohydrodynamics, and ASTR 75 High-Energy Astrophysics, all built around student projects. With support from Vittoria Berta, Adrien Soudais, and George Dufresne.
- Radio telescope club: from Winter 2027, students build a small radio telescope and help revive the department’s radio dish.
- Animations and apps: more than 30 plasma animations on YouTube and web apps for intuition building.
- Knowledge base: a growing wiki that helps students start with our tools from day one.
Dartmouth Alumni Spotlight
Margaret Lambdin (2026)
Role: Undergraduate Research Assistant
Focus: Data management and simulation-based inference for PIC simulations
Brigid O’Donnell (2026)
Role: Undergraduate Research Assistant
Focus: Optimization of GPU-accelerated radiation kernels in PIC simulations
Dr. Pranab Deka (2026)
Role: Visiting Postdoctoral Scholar (KU Leuven)
Focus: Radio wave generation at relativistic magnetized shocks.
Nicole Wotring (2025/26)
Role: Undergraduate Research Assistant
Focus: Analyzing and communicating radio wave generation at shocks
Joseph Kuester (2025/26)
Role: Undergraduate Research Assistant
Focus: Electrodynamics in dipolar coordinates
Owen Young (2026)
Role: Undergraduate Research Assistant
Focus: Resonant inverse-Compton drag in magnetar environments
Elise Little (2025)
Role: Undergraduate Research Assistant
Focus: Effective visualization of complex plasma phenomena
Marcos Cebrian (2025)
Role: Undergraduate Research Assistant
Focus: Radio wave propagation, ponderomotive forces
Jazmín Romero Doldán (2025)
Role: Independent Senior Research
Focus: X-ray data analysis with NuSTAR, NICER, and XMM-Newton.
