Relation between Events in the Millimeter-wave Core and Gamma-ray Outbursts in Blazar Jets

TL;DR

This study finds a strong correlation between millimeter-wave events and gamma-ray flares in blazar jets, suggesting that jet dynamics and magnetic turbulence play key roles in high-energy variability.

Contribution

It demonstrates a direct link between VLBA-observed jet features and gamma-ray flares, providing new insights into the timing and physical processes in blazar jets.

Findings

Approximately two-thirds of gamma-ray flares coincide with new superluminal knots or millimeter-wave core flares.

Gamma-ray flux variability can occur on intra-day timescales despite large emission regions.

Jet structure and magnetic turbulence are likely responsible for rapid gamma-ray variability.

Abstract

Analysis of comprehensive monitoring of 34 gamma-ray bright quasars, BL Lac objects, and radio galaxies reveals a close connection between events in the millimeter-wave emission imaged with the VLBA at 43 GHz and flares at gamma-ray and lower frequencies. Roughly 2/3 of the flares are coincident with the appearance of a new superluminal knot and/or a flare in the millimeter-wave "core'" located parsecs from the central engine. This presents a theoretical challenge to explain how the gamma-ray flux can often be variable on intra-day time-scales. Possible answers to this include very narrow opening angles of the jet, small volume filling factors of the highest energy electrons, chaotic magnetic fields, and turbulent velocity fields relative to the mean jet flow.