Polarization and photometric observations of the gamma-ray blazar PG 1553+113

TL;DR

This study reports optical photo-polarimetric observations of the gamma-ray blazar PG 1553+113, revealing significant inter-night polarization variations without notable flux changes, contributing to understanding blazar polarization behavior.

Contribution

It provides the first detailed optical polarization variability analysis of PG 1553+113, highlighting polarization changes at inter-night scales in a gamma-ray emitting blazar.

Findings

Significant inter-night polarization percentage variations.

No significant intra-night polarization or flux variability.

Polarization angle changes are common in gamma-ray blazars.

Abstract

We present the results of an observational photo-polarimetry campaign of the blazar PG 1553+113 at optical wavelengths. The blazar was recently detected at very high energies (> 100 GeV) by the H.E.S.S and MAGIC gamma-ray Cherenkov telescopes. Our high-temporal resolution data show significant variations in the linear polarization percentage and position angle at inter-night time-scales, while at shorter (intra-night) time-scales both parameters varied less significantly, if at all. Changes in the polarization angle seem to be common in gamma-ray emitting blazars. Simultaneous differential photometry (through the B and R bands) shows no significant variability in the total optical flux. We provide B and R magnitudes, along with a finding chart, for a set of field stars suitable for differential photometry.