'Spectro-temporal' variabilities and possible physical mechanism for Jet ejections

TL;DR

This study analyzes spectro-temporal variations during jet ejections in Galactic black hole sources, revealing local softening phenomena before radio flares, which may be driven by mechanisms other than Keplerian accretion rate changes.

Contribution

It identifies and characterizes local softening events during outbursts, providing insights into jet ejection mechanisms and challenging existing accretion models.

Findings

Local softening occurs before radio flares in multiple sources.

Spectro-temporal properties change rapidly during softening episodes.

Local softening resembles soft state but occurs within intermediate states.

Abstract

In this paper, we attempt to find out the `spectro-temporal' characteristics during the jet ejection, of several outbursting Galactic black hole sources based on RXTE-PCA/HEXTE data in the energy band of 2 - 100 keV. We present results of detailed analysis of these sources during the rising phase of their outburst, whenever simultaneous or near-simultaneous X-ray and Radio observations are `available'. We find that before the peak radio flare (transient jet) a few of the sources (in addition to those reported earlier) exhibit `local' softening within the soft intermediate state itself. Except the duration, all the properties of the `local' softening (QPO not observed, reduction in total rms, soft spectra) are observed to be similar to the canonical soft state. We find similar `local' softening for the recent outburst of V404 Cyg also based on SWIFT observations. Fast changes in the `spectro-temporal' properties during the `local' softening implies that it may not be occurring due to change in Keplerian accretion rate. We discuss these results in the framework of the magnetized two component advective flow model.