Journal Article

Multicomponent and variable velocity galactic outflow in cosmological hydrodynamic simulations

Jun-Hwan Choi and Kentaro Nagamine

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 410, issue 4, pages 2579-2592
Published in print February 2011 | ISSN: 0035-8711
Published online January 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.17632.x
Multicomponent and variable velocity galactic outflow in cosmological hydrodynamic simulations

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We develop a new ‘multicomponent and variable velocity’ (MVV) galactic outflow model for cosmological smoothed particle hydrodynamic (SPH) simulations. The MVV wind model reflects the fact that the wind material can arise from different phases in the interstellar medium, and the mass-loading factor in the MVV model is a function of the galaxy stellar mass. We find that the simulation with the MVV outflow has the following characteristics: (i) the intergalactic medium (IGM) is hardly heated up, and the mean IGM temperature is almost the same as in the no-wind run; (ii) it has lower cosmic star formation rates (SFRs) compared to the no-wind run, but higher SFRs than the constant velocity wind run; (iii) it roughly agrees with the observed IGM metallicity, and roughly follows the observed evolution of Ω(C iv); and (iv) the lower mass galaxies have larger mass-loading factors, and the low-mass end of galaxy stellar mass function is flatter than in the previous simulations. Therefore, the MVV outflow model mildly alleviates the problem of too steep galaxy stellar mass function seen in the previous SPH simulations. In summary, the new MVV outflow model shows reasonable agreement with observations and gives better results than the constant-velocity wind model.

Keywords: methods: numerical; galaxies: evolution; galaxies: formation; galaxies: high-redshift; galaxies: luminosity function, mass function; cosmology: theory

Journal Article.  9788 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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