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

Part of: IAU Issue 315 - From Interstellar Clouds...

Published online by Cambridge University Press:  12 September 2016

Chang-Goo Kim  and
Eve C. Ostriker
Chang-Goo Kim
Affiliation:
Department of Astrophysical Sciences, Princeton University 4 Ivy Lane, Princeton, New Jersey, USA08544 email: [email protected], [email protected]
Eve C. Ostriker
Affiliation:
Department of Astrophysical Sciences, Princeton University 4 Ivy Lane, Princeton, New Jersey, USA08544 email: [email protected], [email protected]
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Abstract

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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, ηc≡ Pc/ΣSFR (in suitable units), for each pressure component. The turbulent and thermal feedback yields are the same for HD and MHD simulations, ηth ~ 1 and ηturb ~ 4, consistent with the theoretical expectations. In MHD simulations, turbulent magnetic fields are rapidly generated by turbulence, and saturate at a level corresponding to ηmag,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.

Keywords

galaxies: ISMgalaxies: star formationgalaxies: magnetic fieldsturbulenceMHDmethods: numerical
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 11 , Symposium S315: From Interstellar Clouds to Star-Forming Galaxies: Universal Processes? , August 2015 , pp. 38 - 41
Copyright
Copyright © International Astronomical Union 2016 

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