Tidal dwarf galaxies in cosmological simulations

TL;DR

This paper reports the first identification of tidal dwarf galaxy candidates in cosmological simulations, showing their formation across diverse environments and linking their properties to cosmic structure formation.

Contribution

It introduces the detection of TDG candidates in high-resolution cosmological simulations, expanding understanding beyond idealised models.

Findings

TDG candidates form in various cosmological environments.

Properties of TDGs are influenced by cosmic structure formation.

Current simulations can identify gravitationally bound tidal structures.

Abstract

The formation and evolution of gravitationally bound, star forming substructures in tidal tails of interacting galaxies, called tidal dwarf galaxies (TDG), has been studied, until now, only in idealised simulations of individual pairs of interacting galaxies for pre-determined orbits, mass ratios, and gas fractions. Here, we present the first identification of TDG candidates in fully cosmological simulations, specifically the high-resolution simulations of the EAGLE suite. The finite resolution of the simulation limits their ability to predict the exact formation rate and survival timescale of TDGs, but we show that gravitationally bound baryonic structures in tidal arms already form in current state-of-the-art cosmological simulations. In this case, the orbital parameter, disc orientations as well as stellar and gas masses and the specific angular momentum of the TDG forming galaxies are a direct consequence of cosmic structure formation. We identify TDG candidates in a wide range of environments, such as multiple galaxy mergers, clumpy high-redshift (up to z = 2) galaxies, high-speed encounters, and tidal interactions with gas-poor galaxies. We present selection methods, the properties of the identified TDG candidates and a roadmap for more quantitative analyses using future high-resolution simulations.