The post-infall evolution of a satellite galaxy

TL;DR

This paper introduces a new local-region simulation method to study how hot galactic coronae influence the chemodynamical evolution of infalling dwarf galaxies, revealing transformation into streams and star formation triggered by environmental effects.

Contribution

It presents a novel simulation approach focusing on the local environment of infalling dwarfs, improving understanding of their evolution under hot corona influence.

Findings

Dwarfs can transform into streams due to ram pressure and tidal forces.

Hot coronae can trigger star formation in dwarf outskirts.

Dwarfs retain gas longer if they form stars post-infall, affecting metallicity.

Abstract

As galaxy simulations increase in resolution more attention is being paid towards the evolution of dwarf galaxies and how the simulations compare to observations. Despite this increasing resolution we are however, far away from resolving the interactions of satellite dwarf galaxies and the hot coronae which surround host galaxies. We describe a new method which focuses only on the local region surrounding an infalling dwarf in an effort to understand how the hot baryonic halo will alter the chemodynamical evolution of dwarf galaxies. Using this method we examine how a dwarf, similar to Sextans dwarf spheroidal, evolves in the corona of a Milky Way like galaxy. We find that even at high perigalacticons the synergistic interaction between ram pressure and tidal forces transform a dwarf into a stream, suggesting that Sextans was much more massive in the past in order survive its perigalacticon passage. In addition the large confining pressure of the hot corona allows gas that was originally at the outskirts to begin forming stars, initially forming stars of low metallicity compared to the dwarf evolved in isolation. This increase in star formation eventually allows a dwarf galaxy to form more metal rich stars compared to one in isolation, but only if the dwarf retains gas for a sufficiently long period of time. In addition, dwarfs which formed substantial numbers of stars post-infall will have a slightly elevated [Mg/Fe] at high metallicity ([Fe/H] -1.5).