How Polarization and Scattering can reveal Geometries, Dynamics, and Feeding of Active Galactic Nuclei

TL;DR

This paper models how polarization and scattering signals can reveal the structure, dynamics, and feeding mechanisms of active galactic nuclei through time-dependent polarization analysis.

Contribution

It introduces a detailed modeling approach for polarization reverberation mapping, linking polarization signals to AGN geometry, dynamics, and inflow rates.

Findings

Time-delays relate polarization to geometry and viewing angle.

In-flow dynamics help constrain cloud optical depth and velocity.

Modeling enables estimation of mass inflow rates.

Abstract

Gaskell et al. (2007) introduced polarization reverberation mapping as a new technique to explore the structure of active galactic nuclei. We present modeling results for the time-dependent polarization signal expected from scattering inside a centrally illuminated spheroid. Such a model setup describes a larger corona surrounding the compact source of an active nucleus. Time-delays between the polarized and the total flux are computed and related to the geometry of the cloud and the viewing angle. When including the in-flow dynamics of the cloud, it is possible to constrain its optical depth and velocity, which enables estimations of the mass inflow rate.