http://arxiv.org/abs/1911.02041
We study specific star formation rate (sSFR) and gas profiles of star forming and green valley galaxies in the \simba\ cosmological hydrodynamic simulation. Star-forming galaxy half-light radii ($R_{\textrm{half}}$) at $z=0$ agree well with observations, but its evolution $\propto(1+z)^{-1.1}$ is somewhat too rapid. We compare \simba\ $z=0$ sSFR radial profiles for main sequence and green valley galaxies to observations \citep{belfiore_2018}. \simba\ shows strong central depressions in star formation rate (SFR), specific SFR, and gas fraction in green valley galaxies and massive star-forming systems, qualitatively as observed. This owes primarily to black hole X-ray feedback, which pushes dense central gas outwards; turning off X-ray feedback leads to centrally peaked sSFR profiles as found in other simulations. In conflict with observations, \simba\ yields green valley galaxies with strongly dropping SFR profiles beyond $\gtrsim R_{\textrm{half}}$, regardless of AGN feedback. The central depression owes to lowering the molecular gas content, while the drop in the outskirts owes to a reduced star formation efficiency. \simba’s satellites have higher central sSFR and lower outskirts sSFR than centrals, in qualitative agreement with observations. At $z=2$ \simba\ does not show strong central depressions in massive star-forming galaxies, whereas observations do, suggesting that \simba’s X-ray feedback should be more active at high-$z$. Reproducing the central sSFR depression in $z=0$ green valley galaxies represents a unique success of \simba, but the remaining discrepancies highlight the importance of SFR and gas profiles in constraining the physical mechanisms by which galaxies quench.
S. Appleby, R. Davé, K. Kraljic, et. al.
Thu, 7 Nov 19
7/50
Comments: 18 pages, 10 figures, submitted to MNRAS
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