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| Paper: |
Do Sub-Millimeter Galaxy Number Counts Provide Evidence for a Top-Heavy IMF? |
| Volume: |
440, UP2010: Have Observations Revealed a Variable Upper End of the Initial Mass Function? |
| Page: |
369 |
| Authors: |
Hayward, C. C.; Narayanan, D.; Jonsson, P.; Cox, T. J.; Kereš, D.; Hopkins, P. F.; Hernquist, L. |
| Abstract: |
Theoretical models have had difficulty matching the observed number density of sub-millimeter galaxies (SMGs), causing
some authors (e.g., Baugh et al. 2005) to suggest that SMGs provide evidence for a top-heavy initial mass function (IMF).
To test this claim, we have, for the first time, combined high-resolution 3-D hydrodynamic simulations of isolated and merging massive,
gas-rich galaxies, radiative transfer, and a semi-empirical merger rate model to predict the number density of SMGs.
Our model can reproduce the observed SMG number density even when using a standard (Kroupa) IMF. The agreement
is due to a combination of relatively long sub-mm duty cycles for mergers (a few times 108 years for our most massive models),
which owe to our combination of high-resolution 3-D hydrodynamic simulations and dust radiative transfer;
sufficient number densities of massive, gas-rich mergers; and the decrease in sub-mm counts observed by recent deep/wide
surveys (e.g., Austermann et al. 2010) relative to previous surveys. Our results suggest that the observed SMG number counts
do not provide evidence for a top-heavy IMF at high redshift. |
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