Possible optical counterparts of ULXs in NGC 1672

Abstract

In this study, we use archival data from Hubble Space Telescope (HST), Chandra, XMM-Newton, and Swift-XRT, to probe the nature of 9 (X1-X9) candidate ultraluminous X-ray sources (ULXs) in NGC 1672. Our study focuses on using the precise source positions obtained via improved astrometry based on Chandra and HST observations to search for and identify optical counterparts for these ULXs. Unique optical counterparts are identified for X2 and X6; two potential counterparts were determined for X1, X5, and X7 within the respective error radii while no optical counterparts were found for the remaining four sources. Based on spectral energy distributions, X-ray, and optical temporal analyses, some evidences about the nature of X1 and X2 were obtained.