3C454.3 reveals the structure and physics of its 'blazar zone'

TL;DR

This paper uses multi-wavelength observations of 3C454.3 to locate its 'blazar zone' near 10 parsecs, revealing insights into jet dissipation, high-energy radiation mechanisms, and variability patterns.

Contribution

It identifies the 'blazar zone' at about 10 parsecs, linking it to the hot dust region and proposing dissipation via reconfinement shocks with inverse Compton scattering as the main high-energy process.

Findings

The 'blazar zone' is located at approximately 10 parsecs from the core.

High gamma-to-synchrotron luminosity ratios occur during low luminosity states.

X-ray and gamma-ray emissions are likely produced by inverse Compton scattering of IR photons.

Abstract

Recent multi-wavelength observations of 3C454.3, in particular during its giant outburst in 2005, put severe constraints on the location of the 'blazar zone', its dissipative nature, and high energy radiation mechanisms. As the optical, X-ray, and millimeter light-curves indicate, significant fraction of the jet energy must be released in the vicinity of the millimeter-photosphere, i.e. at distances where, due to the lateral expansion, the jet becomes transparent at millimeter wavelengths. We conclude that this region is located at ~10 parsecs, the distance coinciding with the location of the hot dust region. This location is consistent with the high amplitude variations observed on ~10 day time scale, provided the Lorentz factor of a jet is ~20. We argue that dissipation is driven by reconfinement shock and demonstrate that X-rays and gamma-rays are likely to be produced via inverse Compton scattering of near/mid IR photons emitted by the hot dust. We also infer that the largest gamma-to-synchrotron luminosity ratio ever recorded in this object - having taken place during its lowest luminosity states - can be simply due to weaker magnetic fields carried by a less powerful jet.