High-Redshift Galaxies in Cold Dark Matter Models

Intense, compact, star-forming galaxies are rare in the local Universe but ubiquitous at high redshift. We interpret the 0.1-22 um spectral energy distributions (SED) of a sample of 180 galaxies at 0.05<z<0.25 selected for extremely high surface densities of inferred star formation in the ultraviolet. By comparison with well-established stellar population synthesis models we find that our sample comprises young (~ 60 - 400 Myrs), moderate mass (~ $6\times 10^9$ Msun) star-for...

Using the conditional luminosity function -- the luminosity distribution of galaxies in a dark matter halo as a function of the halo mass -- we present an empirical model to describe the redshift evolution of the rest B-band galaxy luminosity function (LF). The model is compared to measured LFs out to a redshift of 3.5, including LFs of galaxy types separated to red and blue galaxies. The increase in the number density of luminous galaxies, at the bright-end of the LF, can be...

There are mainly two different approaches to measure the cosmic star formation history: direct star formation rate density (SFRD) and stellar mass density rhostar as functions of redshift. Compilations of current observations seem to show a disparity in the two quantities, in the sense that the integral of SFRD is higher than the observed rhostar (after considering gas recycling). Using cosmological smoothed particle hydrodynamics simulations based on the concordance Lambda c...

This work studies the connection between the first galaxies and their hosting dark matter halos in the early Universe when Reionization is concluding. Our numerical models (already presented in an earlier study) trace the star formation history at $z =$ 4 - 8, the galaxy stellar mass function, the stellar-to-halo mass distribution, and other high redshift galaxies statistics. All these predictions are consistent with observations to date and other high-resolution cosmological...

We discuss how the conditions at high redshift differ from those at low redshift, and what the impact is on the galaxy population. We focus in particular on the role of gaseous dissipation and its impact on sustaining high star formation rates as well as on driving star-bursts in mergers. Gas accretion onto galaxies at high redshifts occurs on a halo dynamical time allowing for very efficiently sustained star formation. In addition cold accretion flows are able to drive turbu...

We study the distribution of the star formation rate and metallicity of damped Lyman-alpha absorbers using cosmological SPH simulations of the Lambda cold dark matter model in the redshift range z=0-4.5. Our approach includes a phenomenological model of galactic wind. We find that there is a positive correlation between the projected stellar mass density and the neutral hydrogen column density (NHI) of DLAs for high NHI systems, and that there is a good correspondence in the ...

The galaxy Luminosity Function (LF) has been estimated in the rest frame B luminosity at 0<z<1.25 and at 1700 {\AA} for 2.5<z<4.5 from deep multicolor surveys in the HDF-N, HDF-S, NTT-DF. The results have been compared with a recent version of galaxy formation models in the framework of hierarchical clustering in a flat Cold Dark Matter Universe with cosmological constant. The results show a general agreement for z<= 1, although the model LF has a steeper average slope at the...

We use state-of-art measurements of the galaxy luminosity function (LF) at z=6, 7 and 8 to derive constraints on warm dark matter (WDM), late-forming dark matter (LFDM) and ultra-light axion dark matter (ULADM) models alternative to the cold dark matter (CDM) paradigm. To this purpose we have run a suite of high-resolution N-body simulations to accurately characterise the low mass-end of the halo mass function and derive DM model predictions of the high-z luminosity function....

Using semi-analytic models of galaxy formation, we investigate the properties of $z\sim3$ galaxies and compare them with the observed population of Lyman-break galaxies (LBGs). In addition to the usual quiescent mode of star formation, we introduce a physical model for starbursts triggered by galaxy-galaxy interactions. We find that with the merger rate that arises naturally in the CDM-based merging hierarchy, a significant fraction of bright galaxies identified at high redsh...

Recent observations of the Lyman-break galaxy (LBG) luminosity function (LF) from z~6-10 show a steep decline in abundance with increasing redshift. However, the LF is a convolution of the mass function of dark matter halos (HMF)--which also declines sharply over this redshift range--and the galaxy-formation physics that maps halo mass to galaxy luminosity. We consider the strong observed evolution in the LF from z~6-10 in this context and determine whether it can be explaine...