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

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 27 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 hr for the optical and gamma-ray bands. The rapid microvariability in the optical/near-IR, 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.