Spectropolarimetric monitoring of active galaxy 3C390.3 with 6m telescope SAO RAS in the period 2009-2014

TL;DR

This study presents spectropolarimetric observations of galaxy 3C 390.3 over five years, revealing small polarized continuum lags and evidence of jet and outflow contributions to polarization and emission line regions.

Contribution

First detailed spectropolarimetric monitoring of 3C 390.3 revealing polarization variability, lags, and jet/outflow influences on emission regions.

Findings

Small lag (10-40 days) between unpolarized and polarized continuum.

Polarized continuum region is smaller than broad line region, indicating jet contribution.

Polarized Hα line shows an outflowing component with velocity ~-1200 km/s.

Abstract

Here we present the spectropolarimetric observations of the radio loud active galaxy 3C 390.3 in the period 2009-2014 (24 epochs). The galaxy has been observed with the 6-meter telescope of SAO RAS using the SCORPIO spectropolarimeter. We explore the variability and lags in the polarized light of the continuum and broad H$\alpha$ line. We give the Stokes parameters $Q, U$, degree of linear polarization $P$ and the position angle of the polarization plane, $\varphi$, for 24 epochs. We find a small lag~(10-40 days) between the unpolarized and polarized continuum that is significantly smaller than the estimated lags for the unpolarized broad emission lines (lag(H$\alpha$)$\sim$138-186 and lag(H$\beta$)$\sim$60-79 days). This shows that the region of the variable polarized continuum is significantly smaller than the broad line region, indicating that a part of the polarized continuum is coming from the jet. The lag of the polarized light in the H$\alpha$ line (89-156 days) indicates an additional component to the disc one that has an outflowing velocity of $\sim$-1200 km s$^{-1}$. This region seems to depolarize the polarized broad H$\alpha$ line emitted from the disc and scattered in the inner part of the torus.