Gamma-ray to radio activity and ejection of a VLBI component in the jet of the S5-quasar 0836+710

TL;DR

This study links broad-band flux variations and jet component ejection in the high-redshift quasar S5 0836+710, revealing correlations between multi-wavelength flaring activity and jet dynamics, supported by VLBI observations and shock models.

Contribution

It provides the first detailed correlation between broad-band variability and jet ejection in a high-redshift quasar using multi-frequency VLBI data.

Findings

Jet component ejection coincides with gamma-ray and X-ray flares.

Radio spectral evolution shows a propagation of flaring activity.

Observations support relativistic shock models for jet activity.

Abstract

Broad-band (gamma to radio) variations of the flux density were observed in the first half of 1992 in the luminous high redshift (z = 2.172) quasar S5 0836+710. VLBI monitoring observations during 1993 -- 1996 performed at 86 GHz, 22 GHz, 15 GHz, and 8 GHz show the ejection of a new jet component, which most probably is directly related to a quasi simultaneous gamma-, X-ray, optical flaring activity which was observed in February 1992. During the period 1992 -- 1993 the flaring propagated through the radio spectrum. From several quasi-simultaneous radio spectra taken during this phase of activity, we determine the time evolution of the spectral turnover of the radio spectrum in the S_m-\nu_m diagram. The data indicate a correlation of the jet activity with the variability of the broad-band electromagnetic spectrum of the source. The observational findings are discussed in the framework of relativistic shock models.