Computational Astrophysics

Computational methods are central to astrophysics at KIPAC. Simulations serve as a third pillar of science alongside theory and observation — the only way to study phenomena that unfold over billions of years or occur in environments impossible to recreate in any laboratory. By encoding the physics of gravity, gas dynamics, magnetic fields, radiation, and dark matter into numerical algorithms, KIPAC researchers can follow the evolution of cosmic structure from the first moments after the Big Bang to the present day, and compare these virtual universes to observed data.

KIPAC researchers develop and run simulations across an enormous range of scales and physical regimes:

Cosmological Structure and the Galaxy-Halo Conenction

Large-volume cosmological simulations track the growth of dark matter structure and the formation of galaxies across cosmic time. KIPAC researchers have developed large simulation suites and galaxy-halo connection models that are central to interpreting data from major surveys including DES, DESI, and Rubin LSST. These simulations, combined with machine-learning emulators, enable precision cosmological inference that would otherwise be computationally intractable. Zoom-in simulations of Milky Way-mass halos probe the small-scale structure of dark matter and the formation of dwarf galaxies, testing models for dark matter's particle nature.

First Stars and Cosmic Reionization

Adaptive mesh refinement simulations capture the formation of the first luminous objects in the universe — massive stars that formed from primordial gas just 100 million years after the Big Bang. These simulations span more than 14 orders of magnitude in length scale, following the collapse of gas from cosmological scales down to the birth of individual stars. KIPAC researchers study how these first stars seeded the cosmos with heavy elements and initiated the reionization of the intergalactic medium.

Galaxy Formation and Hydrodynamics

Hydrodynamic simulations follow the complex interplay of gas, stars, dark matter, and feedback processes that shape galaxies. KIPAC researchers have pioneered methods for simulating galaxy formation with high resolution, capturing the turbulent interstellar medium, star formation, supernova feedback, and the amplification of magnetic fields. These simulations reveal how galaxies acquire their structure, how stellar feedback regulates star formation, and how magnetic fields become dynamically important even when starting from negligible initial seeds.

Compact Objects and Plasma Astrophysics

Kinetic plasma simulations and general relativistic magnetohydrodynamics (GRMHD) codes model the extreme environments around black holes and neutron stars. KIPAC researchers have developed models explaining the coherent radio emission of pulsars, the electromagnetic flares from magnetars and merging neutron stars, and the dynamics of relativistic jets from accreting black holes. These simulations require coupling Einstein's general relativity with the physics of high-energy plasmas in some of the most extreme conditions in the universe.

Algorithmic Development

Pushing the frontiers of computational astrophysics requires developing new numerical methods. KIPAC researchers pioneer novel algorithms for following collisionless fluids like dark matter, for coupling radiation transport to hydrodynamics, and for modeling plasmas in curved spacetime. These methods enable simulations that were previously impossible and often find applications beyond astrophysics.

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