Research

In this series of papers, my collaborators and I outline a framework that connects galaxy-scale star formation rates to the timescales of gas cycling on the scales of star-forming regions. This framework can be used to explain many puzzling phenomena including the global inefficiency of star formation, a near-linear correlation between star formation and molecular gas on kiloparsec scales, and self-regulation of star formation in galaxy simulations.
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The structure of the interstellar medium (ISM) is largely shaped by star formation and stellar feedback and therefore its statistical properties imprint invaluable information about these processes. In this work, we explore how the spatial decorrelation of dense gas and young stars on a range of scales depends on the details of star formation and feedback modeling in galaxy simulation.
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Cosmic rays — relativistic particles accelerated in regions of active star formation — constitute a significant fraction of pressure and energy budget in the interstellar medium and therefore they can strongly affect galaxy evolution. The key uncertainty is the way how cosmic rays propagate through galaxies and interact with the (thermal) gas. Recent observations suggest that cosmic ray propagation is significantly slower near star-forming regions than in the average interstellar medium. In this paper, we show that such a reduced propagation qualitatively changes the structure of galaxies suppressing formation of dense gas clumps, particularly in gas-rich unstable galaxies.
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The efficiency at which dense gaseous regions of galactic gas form stars is expected to strongly depend on the small-scale turbulence. In galaxy simulations, turbulent motions on such small scales cannot be resolved. In this paper, we explore how the modeling of star formation can be improved by explicitly modeling unresolved turbulence using the so-called Large Eddy Simulation methodology which is actively used to model turbulent flows in aerospace engineering and geophysical simulations.
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Nonthermal pressure components, such as turbulence and cosmic rays, are some of the key mediators of star formation feedback (see above). In this paper, we explore different numerical schemes for modeling such components in fluid dynamics simulations. We show that the scheme that enforces entropy conservation is a preferred choice. We also propose a simple method for injection of nonthermal energy by shocks and generation of unresolved turbulence which can be used in conjunction with an entropy-conserving scheme.