Research

The primary theme of my research is the fundamental physics of turbulent flows, and its application to a variety of astrophysical phenomena. The incorporation of turbulent processes into theoretical and computational  models has enabled remarkable progress on a wide range of topics in fundamental science. This has particularly been true in astrophysics, where turbulence is now understood to play an essential role in processes ranging from the formation of stars to supernovae explosions. Despite the apparent complexity of the turbulent flows at work in these disparate phenomena, the turbulent cascade concept originally proposed by Kolmogorov endows them with a deep underlying universal scale-invariant structure within the inertial range, independent of the large-scale driving mechanism. Zwicky, von Weizsäcker, and later authors (in particular Larson) noted the significance of this powerful concept, and applied it within an astrophysical context to galaxies and clusters of galaxies, the interstellar medium, and accretion disks. Their seminal work has provided an overarching framework with which we can begin to understand the role turbulence plays in astrophysical processes.

As the result of this tremendous progress, we are in a now at an exciting point in time where we can now begin to answer a number of fundamental, long-standing astrophysical questions by directly comparing simulation against observation.

My own work has focused on two endpoints of stellar evolution -- star formation and supernovae, as well as on the fundamental physics of turbulent fluids. In the context of supernovae, these questions include : Under what conditions do the merger of two white dwarfs lead to a supernova? How does a Chandrasekhar-mass white dwarf first ignite and initiate a subsonic deflagration front that becomes a type Ia supernova? How does the subsonic deflagration develop into a detonation -- through a deflagration-to-detonation (DDT) transition or the gravitationally-confined detonation (GCD)?  In the context of star formation, outstanding questions include : How is turbulence within star-forming giant molecular clouds (GMCs) generated and sustained? What sets the stellar initial mass function (IMF)? What sets the rate at which stars are formed? How are brown dwarfs formed? How are binary stars formed?


My students, collaborators and I have made substantial contributions towards addressing these key questions. Some of my signature accomplishments include :


  • The first-ever simulation revealing a one-armed spiral disk instability in compact object binary mergers. (2015)
  • The first-ever simulation of the development of the magnetorotational instability in compact object binary mergers. (2013)

  • The first-ever simulation of a Type Iax supernova from a near-Chandrasekhar mass white dwarf. (2012)
  • The largest simulation of compressible, homogeneous, isotropic turbulence, including Lagrangian tracers. (2008)
  • The first-ever 3D simulation of a self-consistent detonation of a near-Chandrasekhar mass white dwarf. (2008)
  • The first quantitative theory of the stellar binary period distribution. (2005)