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Computational Astrophysics

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  • How does mass transfer occur in interacting binaries? How do magnetic fields affect this process?
  • What is dark matter? How does it affect large-scale structure formation?
  • How did the first galaxies and quasars form and evolve? What are the observational signatures of these first luminous objects?
  • How did the stars and galaxies we know today arise from the initial conditions of the Big Bang, and how did the process of Cosmic Reionization unfold?
  • What are the properties of the supermassive black holes that power the most distant quasars? How did they form at the cosmic dawn?
  • What is the relationships between supermassive black holes and host galaxies?

Discoveries and Milestones

  • Mercedes Richards created the first hydrodynamic simulations to illustrate the dynamics of mass transfer in Algol-type interacting binaries.
  • Steinn Sigurdsson showed that black holes in dense stellar clusters tend to form segregated sub-clusters and become bound into binaries which then mutually eject each other, leaving most clusters with either zero, one or two black holes, regardless of how many they started with.
  • Yuexing Li has pioneered the numerical modeling of the formation, evolution, and multi-band properties of the most distant galaxies and quasars by combining multi-scale cosmological simulations with multi-wavelength radiative transfer calculations. She has developed essential models of quasar formation, as well as a comprehensive radiative transfer code ART2 ,which has a wide range of applications in modeling both continuum and emission lines from galaxies and quasars.
  • Mercedes Richards has produced the first 3D Doppler tomograms of gas flows beyond the orbital plane in the entire class of interacting binary stars by using a technique called the Radioastronomical Approach.

Current Projects

  • Yuexing Li is conducting computational work to investigate the formation of the first quasars, accretion onto black holes, Lyman-alpha emission from high-redshift galaxies, fossils of the first black holes and galaxies in the Milky Way, and large-scale structure formation.
  • Mercedes Richards is using her SHELLSPEC spectral synthesis code to isolate the spectroscopic contributions of accretion disk, gas stream, hot spot, and other emission structures in 12 Algol binaries. A comparison to observations will then provide constraints on the physical properties of the components of the accretion flows.
  • Qirong Zhu and Yuexing Li are studying the co-evolution of massive black holes and host galaxies from cosmic dawn to present day using a set of high-resolution, hydrodynamic cosmological simulations.
  • Mercedes Richards is using Doppler tomography to produce 2D images of close interacting binaries based on the observed spectra and difference spectra. Such images would otherwise be impossible to obtain since these binaries are unresolved even with the largest telescopes.
  • Shawn Sinawa and Yuexing Li are modeling the observational signatures of the first quasars for JWST and ALMA, using the 3-D radiative transfer code ART2.


  • Faculty
Steinn Sigurdsson
  • Postdocs and Research Associates
Hidenobu Yajima
  • Students
Shawn Sinawa