Misc,

Moving mesh cosmology: characteristics of galaxies and haloes

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(2011)cite arxiv:1109.4638 Comment: 22 pages, 13 figures, MNRAS submitted. Movies and high-resolution images can be found at http://www.cfa.harvard.edu/itc/research/movingmeshcosmology/.

Abstract

We discuss cosmological hydrodynamic simulations of galaxy formation performed with the new moving-mesh code AREPO, which promises higher accuracy compared with the traditional SPH technique that has been widely employed for this problem. We use an identical set of physics in corresponding simulations carried out with the well-tested SPH code GADGET, adopting also the same high-resolution gravity solver. We are thus able to compare both simulation sets on an object-by-object basis, allowing us to cleanly isolate the impact of different hydrodynamical methods on galaxy and halo properties. In accompanying papers, we focus on an analysis of the global baryonic statistics predicted by the simulation codes (Vogelsberger et al. (2011)), and complementary idealized simulations that highlight the differences between the hydrodynamical schemes (Sijacki et al. (2011)). Here we investigate their influence on the baryonic properties of simulated galaxies and their surrounding haloes. We find that AREPO leads to significantly higher star formation rates for galaxies in massive haloes and to more extended gaseous disks in galaxies, which also feature a thinner and smoother morphology than their GADGET counterparts. Consequently, galaxies formed in AREPO have larger sizes and higher specific angular momentum than their SPH correspondents. We show that these differences persist as a function of numerical resolution. While both codes agree to acceptable accuracy on a number of baryonic properties of cosmic structures, our results thus clearly demonstrate that galaxy formation simulations greatly benefit from the use of more accurate hydrodynamical techniques such as AREPO and call into question the reliability of galaxy formation studies in a cosmological context using traditional formulations of SPH. Abridged

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