The Effect of Galactic Feedback on Gas Accretion and Wind Recycling

TL;DR

This paper explores how galactic winds driven by supernovae and active galactic nuclei influence gas accretion, wind recycling, and galaxy fueling, emphasizing the complex interplay and variability in feedback models.

Contribution

It provides a detailed discussion of the effects of galactic feedback on gas inflows and wind recycling, highlighting the dependence on feedback model specifics.

Findings

Wind recycling significantly fuels galaxies at late times.

Recycled gas has higher metallicity and cooling rates.

The amount of wind recycling varies with feedback model details.

Abstract

In the absence of galactic winds, the rate at which gas accretes onto galaxies is determined by the gravitational potential and by radiative cooling. However, outflows driven by supernovae and active galactic nuclei not only eject gas from galaxies, but also prevent gas from accreting in the first place. Furthermore, gas previously ejected from a galaxy can re-accrete onto (the same or a different) galaxy. Because this gas has a high metallicity, its cooling rate is relatively high, which will increase its chances to re-accrete. This complex interplay between gas inflows and outflows is discussed in this chapter. Wind recycling is found to be an important process that fuels galaxies at late times and the recycled gas has different properties than gas accreting for the first time. Quantitative conclusions, however, vary between studies, because the amount of wind recycling is dependent on the details of the feedback model. We discuss these differences, known caveats, and ways to make progress in understanding how galaxies are fed at low redshift.