Synchrotron Flaring Behaviour of Cygnus X-3

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. Methods. 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 Björnsson & 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.

The formation of relativistic plasma structures and their potential role in the generation of cosmic ray electrons

“…This energy transfer could also be the origin of the synchrotron emissions, which we observe from the MQ jets (Lindfors et al, 2007) and during the prompt phase and the afterglow of long GRBs (Piran, 2004;Gruzinov and Waxman, 1999). The collisionless shocks accelerate the electrons and they amplify the magnetic field (Lindfors et al, 2007;Brunetti et al, 2002;Medvedev and Loeb, 1999;Pe'er and Zhang, 2006). The shocks occur, because plasma clouds collide within the jet (internal shocks) or because the jet impacts onto the stationary plasma of the interstellar medium (external shocks).…”

“…The ejection of jets by the MQs in our galactic neighbourhood, such as GRS 1915+105 or Cygnus X-3, can be observed directly (Fender and Belloni, 2004;Lindfors et al, 2007), which makes them suitable for systematic studies of the dynamical processes that occur in the jet and those that are responsible for its ejection in the first place. The coupled disc-jet system is not stationary in time and the accretion disc emissions and the jet speed and structure vary.…”

“…Both these energy densities should also be high to explain the synchrotron outbursts from the shocked MQ jet plasma (Lindfors et al, 2007). The relevance of the ion energy is not yet clear.…”

“…The jets are sources of electromagnetic radiation over a broad frequency band, some of which is attributed to synchrotron radiation (Lindfors et al, 2007;Harris and Krawczynski, 2006;Piran, 2004;Gruzinov and Waxman, 1999). The AGN jets reveal the sources of this radiation, which are the knots and the hot spots (Brunetti et al, 2002).…”

The Giant Flares of the Microquasar Cygnus X-3: X-Rays States and Jets

“…Indeed, such a law is more natural for the evolution of the synchrotron blobs in jets. The synchrotron emission evolutions of two relativistic jets are determined by their conical geometry and an adiabatic expansion of the blobs, which are composed of relativistic electrons embedded in magnetic fields, moving away from the core hollow jets [21,23].…”