Monte-Carlo Applications for Partially Polarized Inverse External-Compton Scattering (MAPPIES) II -- Application to the UV/Soft X-ray Excess in Blazar Spectra

TL;DR

This paper introduces a Monte Carlo simulation code to predict polarization signatures in blazar spectra, aiming to distinguish emission mechanisms behind UV/soft X-ray excesses in blazars.

Contribution

The paper presents the novel MAPPIES Monte Carlo code for polarization-dependent Compton scattering simulations in blazar jets.

Findings

Predicted polarization signatures for AO 0235+164 and 3C 279

Simulated polarization patterns for UV/soft X-ray excesses

Guidance for upcoming polarimetry observations

Abstract

The spectral energy distributions (SEDs) of some blazars exhibit an ultraviolet (UV) and/or soft X-ray excess, which can be modelled with different radiation mechanisms. Polarization measurements of the UV/X-ray emission from blazars may provide new and unique information about the astrophysical environment of blazar jets, and could thus help to distinguish between different emission scenarios. In this paper, a new Monte-Carlo code -- MAPPIES (Monte-Carlo Applications for Partially Polarized Inverse External-Compton Scattering) -- for polarization-dependent Compton scattering is used to simulate the polarization signatures in a model where the UV/soft X-ray excess arises from the bulk Compton process. Predictions of the expected polarization signatures of Compton emission from the soft X-ray excess in the SED of AO 0235+164, and the UV excess in the SED of 3C 279 are made for upcoming and proposed polarimetry missions.