Extreme photo-polarimetric behaviour of the blazar AO 0235+164

TL;DR

This study provides high-temporal-resolution optical photo-polarimetric observations of blazar AO 0235+164, revealing micro-variability and inter-night changes in flux and polarization, and exploring their correlations.

Contribution

First high-temporal-resolution photo-polarimetric analysis of AO 0235+164, uncovering micro-variability and polarization behaviour at very short time-scales.

Findings

Detected significant micro-variability in flux and polarization.

Observed inter-night variations in polarization and flux.

Found no correlation between flux and polarization degree.

Abstract

We present optical photo-polarimetric observations with high temporal resolution of the blazar AO 0235+164. Our data, the first to test the photo-polarimetric behaviour of this object at very short time-scales, show significant micro-variability in total flux, colour index, linear polarization degree, and position angle. Strong inter-night variations are also detected for these parameters. Although no correlation between colour index and total flux was found, our data seem to support the general bluer-when-brighter trend already known for this object. The polarization degree, in turn, shows no correlation with total flux, but a clear trend in the sense that colour index is redder (the spectrum is softer) when the measured polarization is higher.