Synchrotron flaring behaviour of CygnusX-3 during the February-March 1994 and September 2001 outbursts

TL;DR

This study applies a modified shock-in-jet model to radio flaring data of Cygnus X-3, demonstrating its ability to describe outbursts and derive physical jet parameters, thus linking quasar jet models to microquasar phenomena.

Contribution

It adapts the shock-in-jet model for microquasar Cygnus X-3 and shows its effectiveness in modeling outbursts and estimating jet properties.

Findings

The model successfully describes the 1994 and 2001 outbursts.

High-frequency peaking outbursts are shorter in duration.

The method can estimate magnetic field and electron energy density.

Abstract

Aims: In this paper we study whether the shock-in-jet model, widely used to explain the outbursting behaviour of quasars, can be used to explain the radio flaring behaviour of the microquasar Cygnus X-3. Method: We have used a method developed to model the synchrotron outbursts of quasar jets, which decomposes multifrequency lightcurves into a series of outbursts. The method is based on the Marscher & Gear (1985) shock model, but we have implemented the modifications to the model suggested by Bjornsson & Aslaksen (2000), which make the flux density increase in the initial phase less abrupt. We study the average outburst evolution as well as specific characteristics of individual outbursts and physical jet properties of Cyg X-3. Results: We find that the lightcurves of the February-March 1994 and September 2001 outbursts can be described with the modified shock model. The average evolution shows that instead of the expected synchrotron plateau, the flux density is still increasing during the synchrotron stage. We also find that high frequency peaking outbursts are shorter in duration than the ones peaking at lower frequencies. Finally, we show that the method can be used, complementary to radio interferometric jet imaging, for deriving the physical parameters such as the magnetic field strength and the energy density of relativistic electrons in the jet of Cyg X-3.