Noncommutative Geometry Seminar

The interstellar medium (ISM) represents a chaotic, highly nonlinear system in which super-sonic turbulence, gravity, and "feedback" from both massive stars and accretion onto super-massive black holes play a critical role. Yet despite this complexity, there is remarkable regularity observed in a range of properties, and many of the most fundamental unsolved questions in star and galaxy formation revolve around understanding how the interplay of these physical processes produces such regular correlations. I'll discuss how many observed properties of the ISM can be understood as a fundamental consequence of basic properties of super-sonic turbulence, in a rapidly cooling, self-gravitating medium. In doing so, I'll show how the excursion-set formalism, commonly used to describe the formation of large-scale dark matter structure, can be applied to understand the origins of structure in the ISM and star formation, including the mass function and structural properties of giant molecular clouds, the distribution of masses of stars, and the clustering of star formation. This can also be used to study time-dependent evolution of structure even in highly non-linear systems, allowing us to understand many emergent properties of simulations with supersonic turbulence and gravity.