# The beamed jet and quasar core of the distant blazar 4C 71.07

## TL;DR

This study presents a comprehensive multiwavelength analysis of the high-redshift blazar 4C 71.07, examining its jet and quasar core, and deriving physical parameters like luminosity, accretion rate, and black hole mass over two years.

## Contribution

It provides detailed modeling of the big blue bump, correction prescriptions for thermal contributions, and insights into the polarization behavior of the blazar, based on extensive multiwavelength data.

## Key findings

- No persistent flux correlations across frequencies.
- Polarization degree shows no correlation with flux.
- No connection between EVPA rotations and activity.

## Abstract

The object 4C 71.07 is a high-redshift blazar whose spectral energy distribution shows a prominent big blue bump and a strong Compton dominance. We present the results of a two-year multiwavelength campaign led by the Whole Earth Blazar Telescope (WEBT) to study both the quasar core and the beamed jet of this source. The WEBT data are complemented by ultraviolet and X-ray data from Swift, and by gamma-ray data by Fermi. The big blue bump is modelled by using optical and near-infrared mean spectra obtained during the campaign, together with optical and ultraviolet quasar templates. We give prescriptions to correct the source photometry in the various bands for the thermal contribution, in order to derive the non-thermal jet flux. The role of the intergalactic medium absorption is analysed in both the ultraviolet and X-ray bands. We provide opacity values to deabsorb ultraviolet data, and derive a best-guess value for the hydrogen column density through the analysis of X-ray spectra. We estimate the disc and jet bolometric luminosities, accretion rate, and black hole mass. Light curves do not show persistent correlations among flux changes at different frequencies. We study the polarimetric behaviour and find no correlation between polarisation degree and flux, even when correcting for the dilution effect of the big blue bump. Similarly, wide rotations of the electric vector polarisation angle do not seem to be connected with the source activity.