Discriminate among possible origins of the enhanced absorption

Determine whether the enhanced absorption observed during the first interval of the 2015 XMM-Newton observation was produced by a co-rotating interaction region, an accretion wake, a tidal stream, or dense wind filaments and clumps.

Background

The 2015 XMM-Newton data show an interval with an enhanced absorption column and increased hardness. Earlier work tentatively associated this feature with a co-rotating interaction region, but the paper notes that several other large-scale or clumpy structures in the supergiant wind could produce the same observational signature. The available data do not distinguish between these explanations.

References

We caution, however, that the winds of OB supergiants are highly structured, and that other large-scale features, such as an accretion wake, a tidal stream, or dense filaments and clumps, could produce a similar signature; the present data do not allow us to discriminate among these possibilities.

— Spin-down of the accreting magnetar candidate 4U 0114+65: possible first evidence for a strong coupling regime  (2609.11479 - Sanjurjo-Ferrín et al., 10 Sep 2026) in Section 3, Timing analysis; repeated in Section 4, Spectral analysis