Chandra observations of the ULX N10 in the Cartwheel galaxy

TL;DR

This study analyzes Chandra X-ray observations of ULX N10 in the Cartwheel galaxy, suggesting it is likely an accreting binary with a ~100 solar mass black hole, with alternative explanations considered.

Contribution

First detailed spectral analysis of ULX N10 in the Cartwheel galaxy, interpreting it as a black hole binary based on observational data and theoretical models.

Findings

N10 is likely an accreting binary with a ~100 solar mass black hole.

A young supernova interacting with surroundings is a possible alternative.

Future flux increase observations can confirm the true nature.

Abstract

The Cartwheel galaxy harbours more Ultra-Luminous X-ray sources (ULXs) than any other galaxy observed so far, and as such it is a particularly interesting target to study them. In this paper we analyse the three Chandra observations of the brightest ULX (N10) in the Cartwheel galaxy, in light of current theoretical models suggested to explain such still elusive objects. For each model we derive the relevant spectral parameters. Based on self--consistency arguments we can interpret N10 as an accreting binary system powered by a ~100 solar masses black hole. A young supernova strongly interacting with its surroundings is a likely alternative, that can be discarded only with the evidence of a flux increase from future observations.