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Spectropolarimetry of Blazars with SALT

Presentation #106.52 in the session “AGN (Poster)”.

Published onApr 01, 2022
Spectropolarimetry of Blazars with SALT

Spectropolarimetry is a powerful tool that led to the AGN geometric unification scheme and continues to allow us to investigate AGN central regions. Blazars are AGN with a relativistic jet that is aligned with our line-of-sight and whose optical emission is usually dominated by non-thermal synchrotron emission, leading to a continuum linear polarization that is typically greater than a few percent. For other Type 1 AGN, such as quasars, the inclination angle is not well known and due to the direct quasar light, the polarization signal can be diluted, resulting in polarization levels less than a few percent. In this study, we present preliminary results on optical linear polarization percentage and position angle of a sample of southern hemisphere gamma-ray active and quiescent blazars in the redshift range 0.116 < z < 1.522 to determine how the head-on orientation or the presence of a jet influences spectropolarimetric variations of blazars in the broad lines and continuum. The medium resolution (R ~ 2000) optical spectropolarimetric data used for this study were obtained approximately bi-weekly from the Robert Stobie Spectrograph on the Southern African Large Telescope (SALT) in Sutherland, South Africa.

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