Luminosities, Masses and Star Formation Rates of Galaxies at High Redshift (IAU279 conference proceedings)

TL;DR

Recent advances have enabled the identification of high-redshift star-forming galaxies, revealing lower UV luminosity functions and star formation rates at z=6-8, with implications for cosmic reionization and galaxy evolution.

Contribution

This paper compiles recent observational data on high-redshift galaxies, highlighting their luminosities, star formation rates, and implications for reionization, providing a comprehensive overview of the field.

Findings

UV luminosity function at z=6-8 is lower than at z=2-4

High escape fractions are needed for reionization

Lyman-alpha emission drops at z>7

Abstract

There has been great progress in recent years in discovering star forming galaxies at high redshifts (z>5), close to the epoch of reionization of the intergalactic medium (IGM). The WFC3 and ACS cameras on the Hubble Space Telescope have enabled Lyman break galaxies to be robustly identified, but the UV luminosity function and star formation rate density of this population at z=6-8 seems to be much lower than at z=2-4. High escape fractions and a large contribution from faint galaxies below our current detection limits would be required for star-forming galaxies to reionize the Universe. We have also found that these galaxies have blue rest-frame UV colours, which might indicate lower dust extinction at z>5. There has been some spectroscopic confirmation of these Lyman break galaxies through Lyman-alpha emission, but the fraction of galaxies where we see this line drops at z>7, perhaps due to the onset of the Gunn-Peterson effect (where the IGM is opaque to Lyman-alpha).