High-Redshift Galaxies in Cold Dark Matter Models

I summarize current knowledge of galaxy formation with emphasis on the initial conditions provided by the Lambda CDM cosmology, integral constraints from cosmological quantities, and the demographics of high-redshift protogalaxies. Tables are provided summarizing the number density, star formation rate and stellar mass per object, cosmic star formation rate and stellar mass densities, clustering length and typical dark matter halo masses for Lyman break galaxies, Lyman alpha ...

We have shown previously that galaxy counts from the UV to the near-IR are well-fitted by simple evolutionary models where the space density of galaxies remains constant with look-back time while the star-formation rate rises exponentially. We now extend these results, first by using data from the Herschel Deep Field to show that these same models give detailed fits to the faint galaxy r-i:b-r colour-colour diagram. We then use these models to predict the number counts of hig...

Cosmological hydrodynamic simulations have significantly improved over the past several years, and we have already shown that the observed properties of Lyman-break galaxies (LBGs) at z=3 can be explained well by the massive galaxies in the simulations. Here we extend our study to z=6 and show that we obtain good agreement for the LBGs at the bright-end of the luminosity function (LF). Our simulations also suggest that the cosmic star formation rate density has a peak at z= 5...

We study model predictions for three high-redshift galaxy populations: Lyman break galaxies at z~3 (LBGs), optically selected star-forming galaxies at z~2 (BXs), and distant red galaxies at z~2 (DRGs).Our galaxy formation model simultaneously reproduces the abundances, redshift distributions and clustering of all three observed populations. The star formation rates (SFRs) of model LBGs and BXs are lower than those quoted for real samples, reflecting different initial mass fun...

We study the evolution of Lyman Break Galaxies (LBGs) from z=5 to z=0 by tracing the merger trees of galaxies in a large-scale hydrodynamic simulation based on a Lambda cold dark matter model. In particular, we emphasize on the range of properties of the sample selected by the rest-frame V band luminosity, in accordance with recent near-IR observations. The predicted rest-frame V band luminosity function agrees well with the observed one when dust extinction is taken into acc...

What type of objects are being detected as $z\sim 3$ "Lyman break galaxies"? Are they predominantly the most massive galaxies at that epoch, or are many of them smaller galaxies undergoing a short-lived burst of merger-induced star formation? We attempt to address this question using high-resolution cosmological hydrodynamic simulations including star formation and feedback. Our $\Lambda$CDM simulation, together with Bruzual-Charlot population synthesis models, reproduces the...

We present initial results of a survey for star-forming galaxies in the redshift range 3.8 < z < 4.5. This sample consists of a photometric catalog of 244 galaxies culled from a total solid angle of 0.23 square degrees to an apparent magnitude of I_{AB}=25.0. Spectroscopic redshifts in the range 3.61 < z < 4.81 have been obtained for 48 of these galaxies; their median redshift is <z>=4.13. Selecting these galaxies in a manner entirely analogous to our large survey for Lyman b...

We review recent developments in theoretical studies of galaxy formation and evolution. In combination with new data from HST, Keck and other large telescopes, numerical and semi-analytic modelling is beginning to build up a coherent picture of galaxy formation. We summarize the current status of modelling of various galactic properties such as the structure of dark matter halos, the galaxy luminosity function, the Tully-Fisher relation, the colour-magnitude relation for elli...

I describe a semi-analytical model for the formation and evolution of galaxies in hierarchical clustering models, and its predictions for the properties of the galaxy population at high z. The predictions are found to agree well with the observed properties of the Lyman break galaxies found at z sim 3 by Steidel et al. The models predict that the star formation rate per comoving volume should have peaked at z sim 1-2, which also agrees well with recent observational data.

We make use of the deep Karl G. Jansky Very Large Array (VLA) COSMOS radio observations at 3 GHz to infer radio luminosity functions of star-forming galaxies up to redshifts of z~5 based on approximately 6000 detections with reliable optical counterparts. This is currently the largest radio-selected sample available out to z~5 across an area of 2 square degrees with a sensitivity of rms=2.3 ujy/beam. By fixing the faint and bright end shape of the radio luminosity function to...