Two Optical Counterpart Candidates of M82-X1 from HST Observations

Understand

Optical counterparts can provide significant constraints on the physical nature of ultraluminous X-ray sources (ULXs).

• In this letter, we identify six point sources in the error circle of a ULX in M82, namely M82 X-1, by registering Chandra positions onto Hubble Space Telescope images.
• Two objects are considered as optical counterpart candidates of M82 X-1, which show F658N flux excess compared to the optical continuum that may suggest the existence of an accretion disk.
• The spectral energy distributions of the two candidates match well with the spectra for supergiants, with stellar types as F5-G0 and B5-G0, respectively.