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

Abstract

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 with peak 0.3–10 keV luminosities above 1040 erg s−1 (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.