Identify the physical origin of the 32-day modulation

Determine which physical mechanism produces the approximately 32-day, phase-coherent photometric modulation in SN 2018bsz, distinguishing among Lense--Thirring precession of a fallback disk, interaction with circumstellar material structured before the explosion, and post-supernova accretion from a surviving companion.

Background

The modulation is compatible with several mechanisms. Lense--Thirring precession could provide a central-engine clock, structured circumstellar material could produce recurrent ejecta--CSM interaction, and a surviving companion could supply orbitally modulated post-supernova accretion.

Although SN 2018bsz has independent evidence for ejecta--CSM interaction, the photometric data alone do not establish that interaction caused the modulation. The limited number of observed cycles and the absence of uniquely diagnostic spectroscopic or orbital signatures prevent the alternatives from being distinguished.

References

The present data do not uniquely identify a single mechanism.

— A 32-day Quasi-periodic Modulation in the Post-peak Light Curve of the Superluminous Supernova SN 2018bsz  (2609.19984 - K et al., 17 Sep 2026) in Section 5, Discussion, subsection 5.3; Section 6, Conclusion

However, neither the required accreted mass nor the efficiency with which accretion energy is converted into observable optical radiation is constrained by the present observations, and quantitative modelling is required.

— A 32-day Quasi-periodic Modulation in the Post-peak Light Curve of the Superluminous Supernova SN 2018bsz  (2609.19984 - K et al., 17 Sep 2026) in Section 5.3.3, Post-SN binary interaction