Jason Jaacks, Robert Thompson, Kentaro Nagamine
We present the results of a numerical study examining the effect of H_2-based star formation (SF) model on the rest-frame UV luminosity function (UVLF) and star formation rate function (SFRF) of z>=6 galaxies, and the implications for reionization. Using cosmological hydrodynamical simulations outfitted with a new H_2-SF model, we find good agreement with our previous results (non-H_2 SF model) and observations at Muv<=-18. However at Muv>-18, we find that the LF deviates from both our previous work and current observational estimate, producing significantly fewer low luminosity galaxies and exhibiting additional turnover at the faint end. We constrain the redshift evolution of this turnover point using a modified Schechter function that includes additional terms to quantify the turnover magnitude (Muv^t) and subsequent slope ({\beta}). We find that Muv^t evolves from Muv^t=-17.33 (at z=8) to -15.38 (z=6), while {\beta} becomes shallower by {\Delta}{\beta}=0.22 during the same epoch. This occurs in an Muv range which will be observable by JWST. By integrating the SFRF, we determine that even though H_2-SF model significantly reduces the number density of low luminosity galaxies at Muv>-18, it does not suppress the total SFR density enough to affect the capability of SF to maintain reionization.
View original:
http://arxiv.org/abs/1301.5270
No comments:
Post a Comment