Numerical simulations of dwarf galaxy merger trees

TL;DR

This study uses high-resolution N-body/SPH simulations based on merger trees to explore how different merger histories affect dwarf galaxy properties, providing insights into their observable characteristics.

Contribution

It introduces a computationally efficient simulation approach incorporating merger trees to analyze the impact of merger history on dwarf galaxy evolution.

Findings

Merger history significantly influences dwarf galaxy properties.

Type (i) merger trees produce larger, more extended galaxies with higher angular momentum.

Simulated dwarfs resemble observed dwarf galaxies in key aspects.

Abstract

We investigate the evolution of dwarf galaxies using N -body/SPH simulations that incorporate their formation histories through merger trees constructed using the ex- tended Press-Schechter formalism. The simulations are computationally cheap and have high spatial resolution. We compare the properties of galaxies with equal final mass but with different merger histories with each other and with those of observed dwarf spheroidals and irregulars. We show that the merger history influences many observable dwarf galaxy proper- ties. We identify two extreme cases that make this influence stand out most clearly: (i) merger trees with one massive progenitor that grows through relatively few mergers and (ii) merger trees with many small progenitors that merge only quite late. At a fixed halo mass, a type (i) tree tends to produce galaxies with larger stellar masses, larger half-light radii, lower central surface brightness, and since fewer potentially an- gular momentum cancelling mergers are required to build up the final galaxy, a higher specific angular momentum, compared with a type (ii) tree. We do not perform full-fledged cosmological simulations and therefore cannot hope to reproduce all observed properties of dwarf galaxies. However, we show that the simulated dwarfs are not unsimilar to real ones.