Pks 0116+082: An Optically Variable Compact Steep‐spectrum Source in A Narrow‐line Radio Galaxy

Abstract

Polarimetry of the narrow-line radio galaxy PKS 0116+082 at the W. M. Keck telescope shows that it has high and variable optical polarization, which is presumably due to synchrotron radiation. It is not a BL Lac object because it has strong narrow lines, and it is not an optically violent variable quasar because it has no broad lines and the extended galaxy is prominent. VLA and VLBA images show that it is a compact steep-spectrum radio source with most of the emission coming from a region less than 100 mas in size. Of the 25 compact steep-spectrum or gigahertz peaked-spectrum sources measured polarimetrically, four have high optical polarization. One of these has been observed only once, but in the other three, the polarization is variable. This gives an intriguing hint that variability may be a general property of these objects.