Chemo-dynamical evolution of tidal dwarf galaxies. II. The long-term evolution and influence of a tidal field

TL;DR

This study uses chemo-dynamical simulations to explore the long-term evolution of tidal dwarf galaxies over 3 billion years, examining their survival, star formation, and chemical properties under complex tidal and feedback processes.

Contribution

It demonstrates that TDGs can survive long-term despite extreme feedback and environmental effects, providing insights into their evolution and observable characteristics.

Findings

TDGs reach a self-regulated equilibrium star-formation phase.

TDGs become more compact and sustain higher SFRs due to compressive tides.

None of the models are disrupted despite extreme feedback.

Abstract

In a series of papers, we present detailed chemo-dynamical simulations of tidal dwarf galaxies (TDGs). After the first paper, where we focused on the very early evolution, we present in this work simulations on the long-term evolution of TDGs, ranging from their formation to an age of 3 Gyr. Dark-matter free TDGs may constitute a significant component of the dwarf galaxy (DG) population. But it remains to be demonstrated that TDGs can survive their formation phase given stellar feedback processes, the time-variable tidal field of the post-encounter host galaxy and its dark matter halo and ram-pressure wind from the gaseous halo of the host. For robust results the maximally damaging feedback by a fully populated invariant stellar IMF in each star cluster is assumed, such that fractions of massive stars contribute during phases of low star-formation rates. The model galaxies are studied in terms of their star-formation history, chemical enrichment and rotational curves. All models evolve into a self-regulated long-term equilibrium star-formation phase lasting for the full simulation time, whereby the TDGs become significantly more compact and sustain significantly higher SFRs through compressive tides than the isolated model. None of the models is disrupted despite the unphysical extreme feedback, and none of the rotation curves achieves the high values observed in real TDGs, despite non-virial gas accretion phases.