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arXiv · 1511.00018

Feedback Regulated Turbulence, Magnetic Fields, and Star Formation Rates in Galactic Disks

Chang-Goo Kim·Eve C. Ostriker
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Abstract

We use three-dimensional magnetohydrodynamic (MHD) simulations to investigate the quasi-equilibrium states of galactic disks regulated by star formation feedback. We incorporate effects from massive-star feedback via time-varying heating rates and supernova (SN) explosions. We find that the disks in our simulations rapidly approach a quasi-steady state that satisfies vertical dynamical equilibrium. The star formation rate (SFR) surface density self-adjusts to provide the total momentum flux (pressure) in the vertical direction that matches the weight of the gas. We quantify feedback efficiency by measuring feedback yields, η_c\equiv P_c/Σ_SFR (in suitable units), for each pressure component. The turbulent and thermal feedback yields are the same for HD and MHD simulations, η_th~1 and η_ turb~4, consistent with the theoretical expectations. In MHD simulations, turbulent magnetic fields are rapidly generated by turbulence, and saturate at a level corresponding to η_mag,t~1. The presence of magnetic fields enhances the total feedback yield and therefore reduces the SFR, since the same vertical support can be supplied at a smaller SFR. We suggest further numerical calibrations and observational tests in terms of the feedback yields.

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Chang-Goo Kim, Eve C. Ostriker. 2015-10-30. Feedback Regulated Turbulence, Magnetic Fields, and Star Formation Rates in Galactic Disks. https://doi.org/10.1017/s1743921316007225

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