SALT Spectropolarimetry and Self-Consistent SED and Polarization Modeling of Blazars

TL;DR

This paper combines SALT spectropolarimetry with multi-wavelength SED modeling to better understand the physical conditions in gamma-ray blazars, especially constraining black hole mass.

Contribution

It introduces a self-consistent modeling approach that integrates spectropolarimetry and SED data to derive physical parameters of blazar emission regions.

Findings

Constrains magnetic field order in blazar emission zones.

Estimates black hole mass in 4C+01.02 to be around 10^9 solar masses.

Provides insights into thermal contributions to the SED.

Abstract

We report on recent results from a target-of-opportunity program to obtain spectropolarimetry observations with the Southern African Large Telescope (SALT) on flaring gamma-ray blazars. SALT spectropolarimetry and contemporaneous multi-wavelength spectral energy distribution (SED) data are being modelled self-consistently with a leptonic single-zone model. Such modeling provides an accurate estimate of the degree of order of the magnetic field in the emission region and the thermal contributions (from the host galaxy and the accretion disk) to the SED, thus putting strong constraints on the physical parameters of the gamma-ray emitting region. For the specific case of the $\gamma$-ray blazar 4C+01.02, we demonstrate that the combined SED and spectropolarimetry modeling constrains the mass of the central black hole in this blazar to $M_{\rm BH} \sim 10^9 \, M_{\odot}$.