Major and Minor Flares on Cygnus X-3 Revisited

TL;DR

This paper revisits the properties of major and minor flares in Cygnus X-3, revealing differences in their physical characteristics, temporal behavior, and potential mechanisms, including synchrotron expansion and shock models.

Contribution

It provides new insights into the physical conditions and mechanisms behind minor and major flares in Cygnus X-3, highlighting their differences and possible interactions.

Findings

Minor flares have shorter rise times and are closer to the binary.

Minor flares have higher magnetic fields and energy densities than major flares.

Minor flares can occur during major flares, indicating possible coupling.

Abstract

Intense flares at cm-wavelengths reaching levels of tens of Jy have been observed from Cygnus X-3 for many years. This active high mass X-ray binary also has periods of quenching before major outbursts, and has minor flares at levels of a few hundred mJy. In this paper we show that the minor flares have much shorter rise times and durations suggesting more rapid expansion of the synchrotron radiation emitting material than in the strong flares. They also appear closer to the binary, whereas the large flares form a more developed jet. Calculations of physical conditions show that the minor out-bursts have lower minimum power but have larger magnetic fields and energy densities than the major flares. Minor flares can occur while a major flare is in progress, suggesting an indirect coupling between them. The spectral evolution of the minor flares can be explained by either an expanding synchrotron source or a shock model. The possibility that there is a brightening zone as in SS433 is explored.