Another thread in the tapestry of stellar feedback: X-ray binaries

TL;DR

This paper explores how X-ray binaries (XBs) can significantly influence stellar feedback, especially in dwarf galaxies, by depositing energy into the interstellar medium, with effects varying due to stochastic processes and metallicity.

Contribution

It introduces the role of X-ray binaries as a potentially dominant and stochastic source of stellar feedback, especially in low-mass galaxies, and discusses their impact relative to supernova feedback.

Findings

XBs can deposit a high fraction of their power into the interstellar medium.

Stochastic effects cause large variability in XB feedback, influencing dwarf galaxy evolution.

XBF may precede supernova feedback, affecting gas heating and star formation.

Abstract

We consider X-ray binaries (XBs) as potential sources of stellar feedback. XBs observationally appear able to deposit a high fraction of their power output into their local interstellar medium, which may make them a non-negligible source of energy input. The formation rate of the most luminous XBs rises with decreasing metallicity, which should increase their significance during galaxy formation in the early universe. We also argue that stochastic effects are important to XB feedback (XBF) and may dominate the systematic changes due to metallicity in many cases. Large stochastic variation in the magnitude of XBF at low absolute star formation rates provides a natural reason for diversity in the evolution of dwarf galaxies which were initially almost identical, with several percent of such halos experiencing energy input from XBs roughly two orders of magnitude above the most likely value. These probability distributions suggest that the effect of XBF is most commonly significant for total stellar masses between ~10^7 and 10^8 Msun, which might resolve a current problem with modelling populations of such galaxies. We explain how XBs might inject energy before luminous supernovae (SNe) contribute significantly to feedback and how XBs can assist in keeping gas hot long after the last core-collapse SN has exploded. [...] XBF could be especially important to some dwarf galaxies, potentially heating gas without expelling it; the properties of XBF also match those previously derived as allowing episodic star formation. We also argue that the efficiency of SN feedback (SNF) might be reduced when XBF has had the opportunity to act first. In addition, we note that the effect of SNF is unlikely to be scale-free; galaxies smaller than ~100 pc might well experience less effective SNF. (Slightly abbreviated to fit arXiv size limit.)