Searching for the orbital period of the ultraluminous X-ray source NGC 1313 X-2

Abstract

We analysed the longest phase-connected photometric data set available for NGC 1313 X-2, looking for the ~6-day modulation reported by Liu et al.. The folded B-band light curve shows a ~6-day periodicity with a significance slightly larger than 3σ. The low statistical significance of this modulation, along with the lack of detection in the V band, makes its identification uncertain.