Canonical high power blazars

TL;DR

This paper explores how the spectral energy distribution of high power blazars varies with the location of jet energy dissipation, emphasizing the role of external radiation fields and their impact on high-energy emission.

Contribution

It provides a detailed analysis of how the dissipation region affects the blazar SED using standard models for accretion, jet magnetic fields, and external radiation, highlighting the importance of dissipation beyond the broad line region.

Findings

Inverse Compton flux dominates the bolometric output in canonical jets.

Dissipation beyond the broad line region yields high inverse Compton to synchrotron ratios.

High redshift blazars can probe cosmic optical to UV backgrounds.

Abstract

The jets of powerful blazars propagate within regions relatively dense of radiation produced externally to the jet. This radiation is a key ingredient to understand the origin of the high energy emission of blazars, from the X-ray to the gamma-ray energy band. These external radiation fields control the amount of the inverse Compton radiation with respect to the synchrotron flux. Therefore the predicted spectral energy distribution (SED) will depend on where the jet dissipates part of its energy to produce the observed radiation. We investigate in detail how the SED changes as a function of the location of the jet dissipation region, by assuming rather "standard" (i.e. "canonical") prescriptions for the accretion disk and its X-ray corona, the profile of the jet magnetic field and the external radiation. The magnetic energy density of a "canonical" jet almost never dominates the radiative cooling of the emitting electrons, and consequently the inverse Compton flux almost always dominates the bolometric output. This is more so for large black hole masses. Dissipation taking place beyond the broad line region is particularly interesting, since it accounts in a simple way for the largest inverse Compton to synchrotron flux ratios accompanied by an extremely hard X-ray spectrum. Furthermore it makes the high power blazars at high redshift useful tools to study the optical to UV cosmic backgrounds.