X-raying the galaxy pair Arp 41: no collision in NGC 1232 and three ultraluminous sources in NGC 1232A

TL;DR

This study used Chandra X-ray observations to investigate the galaxy pair NGC 1232 / NGC 1232A, finding no evidence of collision in NGC 1232 and identifying three ultraluminous X-ray sources in NGC 1232A, which resembles NGC 1313.

Contribution

The paper provides the first detailed X-ray analysis of NGC 1232 / NGC 1232A, revealing the ULX population in NGC 1232A and clarifying the interaction status of the pair.

Findings

No diffuse emission in NGC 1232, contradicting previous claims.

NGC 1232A hosts three ULXs with luminosities above 10^{40} erg/s.

NGC 1232A resembles NGC 1313 in properties.

Abstract

We studied the apparent galaxy pair NGC 1232 / NGC 1232A with Chandra, looking for evidence of interactions and collisions. We report that there is no cloud of diffuse emission in NGC 1232, contrary to previous claims in the literature. Instead, we find that the small "companion" galaxy NGC 1232A contains three ultraluminous X-ray sources (ULXs) with peak 0.3-10 keV luminosities above 10^{40} erg/s (assuming a cosmological distance of 93 Mpc for this galaxy). For its mass, morphology, metal abundance and bright ULX population, NGC 1232A is analogous to the more nearby late-type spiral NGC 1313.