Ultraluminous X-ray Sources in Interacting Galaxies

TL;DR

This paper reviews how X-ray observations of nearby galaxies reveal that ultraluminous X-ray sources (ULXs) are linked to recent star formation, especially in interacting galaxies with high star formation rates.

Contribution

It introduces new findings on the association of ULXs with young star-forming regions and explores their maximum luminosity in galaxies with high star formation activity.

Findings

ULXs are found in regions as young as or younger than HII regions.

Most luminous point-like X-ray sources are high-mass X-ray binaries.

ULXs are preferentially located in interacting galaxies with high star formation rates.

Abstract

I give a brief review of how X-rays from nearby galaxies are used as direct tracers of recent star formation. This leads to the conclusion that it is the most luminous point-like sources that are associated with star formation and that the majority of these are high-mass X-ray binaries.I then discuss a recent study that shows that ULXs are preferentially found in regions as young as or younger than typical HII regions in their host galaxies. Finally, I describe a new study that attempts to determine the maximum luminosity of ULXs in the local universe by searching for them in interacting galaxies where the star formation rate is high.