Spatially resolved star formation image and the ULX population in NGC2207/IC2163

TL;DR

This study uses high-resolution X-ray and star formation rate images to analyze the spatial distribution of ULXs in NGC 2207/IC 2163, revealing a strong correlation between ULX numbers and local star formation activity.

Contribution

It provides the first spatially-resolved analysis linking ULX populations with star formation rates in a colliding galaxy pair.

Findings

ULX numbers correlate with local star formation rate densities.

ULX luminosities do not strongly correlate with star formation rates.

The galaxy hosts one of the highest ULX populations per unit mass reported.

Abstract

The colliding galaxy pair NGC 2207/IC 2163, at a distance of ~39 Mpc, was observed with Chandra, and an analysis reveals 28 well resolved X-ray sources, including 21 ultraluminous X-ray sources (ULXs) with Lx > 10^39 erg/s, as well as the nucleus of NGC 2207. The number of ULXs is comparable with the largest numbers of ULXs per unit mass in any galaxy yet reported. In this paper we report on these sources, and quantify how their locations correlate with the local star formation rates seen in spatially-resolved star formation rate density images that we have constructed using combinations of Galex FUV and Spitzer 24um images. We show that the numbers of ULXs are strongly correlated with the local star formation rate densities surrounding the sources, but that the luminosities of these sources are not strongly correlated with star formation rate density.