The link between broad emission line fluctuations and non-thermal emission from the inner AGN jet

TL;DR

This study explores how non-thermal emission from jets in radio-loud AGN influences broad emission line fluctuations, revealing that some broad-line material is located in jet-ionized outflows, affecting black hole mass estimates.

Contribution

It provides new evidence linking jet-related non-thermal emission to broad-line region dynamics in radio-loud AGN, challenging traditional reverberation mapping assumptions.

Findings

Broad-line emission can originate from jet-ionized outflows at >1pc.

Jet emission impacts black hole mass estimates from line widths.

Non-thermal continuum emission influences broad-line variability.

Abstract

AGN reverberate when the broad emission lines respond to changes of the ionizing thermal continuum emission. Reverberation measurements have been commonly used to estimate the size of the broad-line region (BLR) and the mass of the central black hole. However, reverberation mapping studies have been mostly performed on radio-quiet sources where the contribution of the jet can be neglected. In radio-loud AGN, jets and outflows may affect substantially the relation observed between the ionizing continuum and the line emission. To investigate this relation, we have conducted a series of multiwavelength studies of radio-loud AGN, combining optical spectral line monitoring with regular VLBI observations. Our results suggest that at least a fraction of the broad-line emitting material can be located in a sub-relativistic outflow ionized by non-thermal continuum emission generated in the jet at large distances (> 1pc) from the central engine of AGN. This finding may have a strong impact on black hole mass estimates based on measured widths of the broad emission lines and on the gamma-ray emission mechanisms.