Simulations at the Dwarf Scale: From Violent Dwarfs at Cosmic Dawn and Cosmic Noon to Quiet Discs today

TL;DR

This paper reviews cosmological hydrodynamical simulations of dwarf galaxy formation across different epochs, highlighting their evolution from violent, high-efficiency star-forming systems to quieter, disc-dominated galaxies today.

Contribution

It provides a comparative analysis of dwarf galaxy formation at various cosmic times using a large suite of simulations, including new predictions for JWST observations.

Findings

FirstLight simulations predict high star formation efficiencies in early dwarfs.

Dwarfs at cosmic noon are dispersion-dominated with elongated shapes.

Low-redshift dwarfs form stable discs consistent with observed scaling relations.

Abstract

Dwarf galaxies with stellar masses around 10^9 Msun can be explored at high and low redshifts and they give a glimpse of the different conditions of galaxy formation at different epochs. Using a large sample of about 300 zoom-in cosmological hydrodynamical simulations of galaxy formation I will briefly describe the formation of dwarfs at this mass scale at 3 different epochs: cosmic dawn (Ceverino, Klessen, Glover 2018), cosmic noon (Ceverino, Primack, Dekel 2015), and today (Ceverino et al. 2017). I will describe the FirstLight simulations of first galaxies at redshifts 5-15. These first dwarfs have extremely high star formation efficiencies due to high gas fractions and high gas accretion rates. These simulations will make predictions that will be tested for the first time with the James Webb Space Telescope (JWST). At cosmic noon, z = 2, galaxy formation is still a very violent and dynamic process. The VELA simulations have generated a set of dispersion-dominated dwarfs that show an elongated morphology due to their prolate dark-matter halos. Between z = 1 and 0, the AGORA simulation shows the formation of a low-mass disc due to slow gas accretion. The disc agrees with many local scaling relations, such as the stellar-mass-halo-mass and the baryonic Tully-Fisher relation.