K. Nagamine et al., Luminosity density of galaxies and cosmic star formation rate from a cold dark matter hydrodynamical simulations, ASTROPHYS J, 541(1), 2000, pp. 25-36
We compute the cosmic star formation rate (SFR) and the rest-frame comoving
luminosity density in various passbands as a function of redshift using la
rge-scale Lambda CDM hydrodynamical simulations, with the aim of understand
ing their behavior as a function of redshift. To calculate the luminosity d
ensity of galaxies, we use an updated isochrone synthesis model that takes
metallicity variations into account. The computed SFR and the UV luminosity
density have a steep rise from z = 0 to 1, a moderate plateau between z =
1-3, and a gradual, decrease beyond z = 3. The raw calculated results are s
ignificantly above the observed luminosity density, which can be explained
either by dust extinction or the possibly inappropriate input parameters of
the simulation. We model the dust extinction by introducing a parameter f;
the fraction of the total stellar luminosity (not galaxy population) that
is heavily obscured and thus only appears in the far-infrared to submillime
ter wavelength range. When we correct our input parameters (baryon mass-den
sity and the yield of metals) to the current best estimate and apply dust e
xtinction with f = 0.65, the resulting luminosity density fits various obse
rvations reasonably well, including the present stellar mass density, the l
ocal B-band galaxy luminosity density, and the FIR-to-submillimeter extraga
lactic background. Our result is consistent with the picture that similar t
o 2/3 of the total stellar emission is heavily obscured by dust and observe
d only in the FIR. The rest of the emission is only moderately obscured, wh
ich can be observed in the optical to near-IR wavelength range. We also arg
ue that the steep falloff of the SFR from z = 1 to 0 is partly due to the s
hock-heating of the universe at late times, which produces gas that is too
hot to easily condense into star-forming regions.