Determine the recovery time of the undetected pulsations

Determine when the long-term Swift/BAT pulsations of 4U 0114+65 recover following their disappearance in 2025.

Background

In 2025, the long X-ray pulsations of the accreting neutron-star system 4U 0114+65 became undetectable in Swift/BAT monitoring for at least six months. The XMM-Newton observation reported in the paper detected weak pulsations, showing that the underlying spin modulation persisted, but the recovery time of the pulsations in the long-term hard-X-ray monitoring remained undetermined.

References

In 2025, 4U~0114+65 entered a rare state in which its pulsations became undetectable in the Swift/BAT monitoring and remained so for at least the subsequent six months, with an unknown recovery time.

— 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 1, Introduction