Spectropolarimetry of 3CR68.1: A Highly Inclined Quasar

We present Keck spectropolarimetry of the highly polarized radio-loud quasar 3CR68.1 (z = 1.228, V = 19). The polarization increases from 5% in the red (4000Å rest-frame) to >10% in the blue (1900Å rest-frame). The broad emission lines are polarized the same as the continuum, which shows that 3CR68.1 is not a blazar as it has sometimes been regarded in the past. We also present measurements of the emission lines and a strong, blueshifted, associated absorption line system, as well as a detection at the emission-line redshift of Ca II K absorption, presumably from stars in the host galaxy. 3CR68.1 belongs to an observationally rare class of highly polarized quasars that are neither blazars nor partially-obscured radio-quiet QSOs. Taking into account 3CR68.1’s other unusual properties, such as its extremely red spectral energy distribution and its extreme lobe dominance, we explain our spectropolarimetric results in terms of unified models. We argue that we have a dusty, highly inclined view of 3CR68.1, with reddened scattered (polarized) quasar light diluted by even more dust-reddened quasar light reaching us directly from the nucleus. Subject headings: line: profiles — quasars: emission lines — quasars: general — quasars: absorption lines — galaxies: individual: 3CR68.1 — techniques:polarimetric Based on observations at the W. M. Keck Observatory. Currently at Johns Hopkins University, [email protected]. The National Optical Astronomy Observatories are operated by the Association of Universities for Research in Astronomy under cooperative agreement with the National Science Foundation.