Polarimetric periodicity and frequency content in Deneb

Determine whether Deneb’s linear polarization time series exhibits any persistent periodicity or preferred polarization direction by performing a robust frequency analysis of a sufficiently long and well-sampled sequence of normalized Stokes parameters in the SDSS g′ band and other filters.

Background

The observations reveal polarization variations of hundreds of ppm on week-long timescales, with one extreme event and otherwise irregular behavior. The authors find no obvious periods or preferred polarization directions in the current dataset.

They explicitly state that the available data are insufficient for robust frequency analysis, leaving unresolved whether there exist persistent periodicities or favored orientations in the polarimetric variability.