The early evolution of tidal dwarf galaxies

TL;DR

This study uses chemodynamical models to explore how tidal dwarf galaxies evolve without dark matter, showing they can sustain star formation for over 300 million years and match observed properties of Local Group dwarf spheroidals.

Contribution

It provides the first detailed chemodynamical simulations of dark matter-free dwarf galaxies, highlighting the importance of gas distribution over dark matter in their evolution.

Findings

Dwarf galaxies without dark matter can sustain star formation for over 300 Myr.

Chemical properties of models match those of Local Group dwarf spheroidals.

Gas distribution influences galaxy evolution more than dark matter depth.

Abstract

Context: Dwarf galaxies can arise from self-gravitating structures emerging from tidal tails. What fraction of the known dwarf galaxies in the Local Universe can have this origin is still a matter of debate. Aims: In our effort to understand the origin and evolution of tidal dwarf galaxies and their correspondence with local objects, the first step is to understand how these galaxies (which are supposed to have a limited amount of dark matter) react to the feedback of the ongoing star formation. Methods: We make use of 2-D chemodynamical calculations in order to study the early evolution of isolated, dark matter-free dwarf galaxies. We present models in which feedback parameters are varied. We also compare the results with dark matter-dominated dwarf galaxy models. Results: All the considered models show that the star formation proceeds for more than 300 Myr, therefore dwarf galaxies without large dark matter halos are not necessarily quickly destroyed. The chemical evolution of these objects is consistent with the main chemical properties of the dSphs of the Local Group. Models with large dark matter halos show results consistent with models free of dark matter, indicating that the distribution of gas is more important than the depth of the potential well in determining the global behaviour of dSph-sized dwarf galaxies.