The Multifrequency Campaign on 3C 279 in January 2006

TL;DR

This study presents a multifrequency observational campaign of blazar 3C 279 during an optical high-state, revealing that high-energy synchrotron emission varies while inverse-Compton emission remains stable, explained by changes in electron energy distribution.

Contribution

It provides the first detailed multifrequency SED comparison between high and low optical states of 3C 279, highlighting the role of electron energy cutoff changes in variability.

Findings

High-energy synchrotron emission varies between states.

Inverse-Compton emission remains unchanged.

Variability explained by a change in the low-energy cutoff of electrons.

Abstract

We present the results of a multifrequency campaign from radio to hard X-ray energies on the blazar 3C 279 during an optical high-state in January 2006. We give the observational results (multifrequency light curves and spectra) and compile an SED. This complements an SED from an optical low-state in June 2003. Surprisingly the two SEDs differ only in their high-energy synchrotron emission (near-IR - UV), while the low-energy inverse-Compton emission (X- to Gamma-rays) remained unchanged. By interpreting with a steady-state leptonic emission model, the variability among the SED can be reproduced by a change solely of the low-energy cutoff of the relativistic electron distribution. In an internal shock model for blazar emission, such a change could e.g. achieved through a varying relative Lorentz factor of colliding shells producing internal shocks in the jet.