The Variable Optical Polarization and FERMI Observations of PMN J0948+0022

TL;DR

This study presents multi-wavelength observations of PMN J0948+0022, revealing blazar-like rapid variability and polarization, but lacking conclusive evidence of jet orientation, thus contributing to understanding its nature.

Contribution

It provides detailed optical and gamma-ray variability data of PMN J0948+0022, highlighting its blazar-like features and raising questions about its jet orientation and emission mechanisms.

Findings

Rapid optical and gamma-ray variability (~4 hours) observed.

Significant and variable optical polarization detected.

No clear correlation between gamma-ray and optical behavior found.

Abstract

We report on observations of the {\gamma}-ray and optical photopolarimetric behavior of the radio-loud, narrow line type-1 Seyfert galaxy PMN J0948+0022 over a twenty seven month period. As this object has recently been suggested to represent a prototype of an emerging class of blazar-like objects, the observed properties are compared to those of blazars. We extract doubling timescales of roughly 4 hours for the optical and {\gamma}-ray bands. The rapid microvariability in the optical/NIR, significant and variable optical polarization, and strong yet rapidly-variable {\gamma}-ray emission we observe for PMN J0948+0022 are all classical observational characteristics associated with blazars. However, since these observations do not show a clear correlation between the {\gamma}-ray and optical behavior, they do not offer conclusive proof that the emissive behavior of PMN J0948+0022 is due to a relativistic jet oriented close to our line of sight.