`Spectro-temporal' characteristics and disk-jet connection of the outbursting black hole source XTE J1859+226

TL;DR

This study analyzes the spectral and temporal behavior of the black hole XTE J1859+226 during its 1999 outburst, revealing insights into disk-jet interactions, spectral evolution, and QPO dynamics using RXTE data.

Contribution

It provides a detailed analysis of the outburst's spectro-temporal evolution, estimates the black hole mass, and explores the disk-jet connection with a focus on corona disruption during ejections.

Findings

QPO frequencies vanish during radio flares, indicating corona disruption.

The spectral evolution follows a typical q-shaped pattern but lacks a canonical soft state.

The corona appears to be evacuated during jet ejections, affecting QPOs and spectral properties.

Abstract

We re-investigated the `spectro-temporal' behaviour of the source XTE J1859+226 in X-rays during its outburst phase in 1999, by analysing the RXTE PCA/HEXTE data in 2 - 150 keV spectral band. Detailed analysis shows that although the evolution pattern of the outburst followed the typical q-shaped profile, an absence of `canonical' soft state and a weak presence of `secondary' emission are observed. The broad-band spectra, modeled with high energy cutoff, shows that the fold-energy increases monotonically in the hard and hard-intermediate states followed by a random variation in the soft-intermediate state. We attempted to estimate the mass of the source based on the evolution of Quasi-Periodic Oscillation (QPO) frequencies during rising phase modeled with the propagating oscillatory shock solution, and from the correlation of photon index and QPO frequency. It is also observed that during multiple ejections (observed as radio flares) the QPO frequencies are not present in the power spectra which is followed by softening of the spectra (disk flux increases or high energy flux decreases). These results are the `possible' indication that the Comptonized corona, which could be responsible for the generation of QPO and for the non-thermal Comptonized component of the spectrum, is disrupted and the matter gets evacuated in the form of jet. We attempted to explain the complex behaviour of the source during the entire outburst and the nature of the disk-jet connection in the context of two different types of accreting flow material, in presence of magnetic field.