High Redshift Galaxy Populations and their Descendants

TL;DR

This study uses galaxy formation models to predict properties and evolutionary outcomes of high-redshift galaxy populations, matching observed distributions and clustering, and tracing their descendants to present-day galaxies.

Contribution

The paper presents a comprehensive model that reproduces observed high-redshift galaxy populations and predicts their evolution and descendants, including clustering and star formation histories.

Findings

Model reproduces observed abundances and clustering of high-redshift galaxies.

Most high-redshift galaxies evolve into red ellipticals by z=0.

Over 70% of massive local galaxies have high-redshift progenitors.

Abstract

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 functions and scatter in model dust properties. About 85% of model galaxies selected as DRGs are star-forming, with SFRs ranging up to 100 M_sun/yr. Model LBGs, BXs and DRGs together account for less than half of all star formation over the range 1.5<z<3.2. Model BXs have metallicities which agree roughly with observation, but model LBGs are only slightly more metal-poor, in disagreement with recent observational results. Model galaxies are predominantly disk-dominated. About 30% of model galaxies with M>10^{11}M_sun are classified as LBGs or BXs at the relevant redshifts, while 65% are classified as DRGs. Almost all model LBGs and BXs are central galaxies, but about a quarter of DRGs are satellites. Half of all LBG descendants at z=2 would be identified as BX's, but very few as DRGs. Clustering increases with decreasing redshift for descendants of all three populations, becoming stronger than that of L^* galaxies by z=0, when many have become satellite galaxies. Their stellar mass growth is dominated by star formation until z~1 and thereafter by mergers. Most LBGs and DRGs end up as red ellipticals, while BXs have a more varied fate. 99% of local galaxies with M>10^{11.5}M_sun are predicted to have at least one LBG/BX/DRG progenitor, and over 70% above 10^{11}M_sun. (abbreviated)