MULTIWAVELENGTH OBSERVATIONS OF PKS 0528+134 IN QUIESCENCE

摘要

We present results of multiwavelength observations of the ultraluminous radio-loud quasar PKS 0528+134 in quiescence in the Fall of 2009. Significant flux variability on a time-scale of several hours was found in the optical regime, accompanied by a weak trend of spectral softening with increasing flux. The optical flux is weakly polarized with rapid variations of the degree and direction of polarization. Optical spectropolarimetry suggests a trend of increasing degree of polarization with increasing wavelength. Together with the spectral variability, this provides evidence for an unpolarized, slowly variable emission component, possibly thermal emission from the accretion disk, contributing towards the blue end of the optical spectrum.