The X-ray spectro-timing properties of a major radio flare episode in Cygnus X-3

TL;DR

This study uses principal component analysis on X-ray data from Cygnus X-3 during a major flare, revealing two dominant variability components linked to inverse-Compton scattering and bremsstrahlung, with implications for wind asymmetry.

Contribution

It introduces a PCA-based approach to dissect X-ray spectral variability in Cygnus X-3 during a flare, identifying key emission mechanisms and their phase-dependent behavior.

Findings

Two main variability components explain almost all X-ray lightcurve variability.

Spectral analysis suggests inverse-Compton scattering and bremsstrahlung as dominant emission processes.

Double-peaked phase profile indicates possible asymmetrical wind interaction.

Abstract

We have performed a principal component analysis on the X-ray spectra of the microquasar Cygnus X-3 from RXTE, INTEGRAL and Swift during a major flare ejection event in 2006 May-July. The analysis showed that there are two main variability components in play, i.e. two principal components explained almost all the variability in the X-ray lightcurves. According to the spectral shape of these components and spectral fits to the original data, the most probable emission components corresponding to the principal components are inverse-Compton scattering and bremsstrahlung. We find that these components form a double-peaked profile when phase-folded with the peaks occurring in opposite phases. This could be due to an asymmetrical wind around the companion star with which the compact object is interacting.