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

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 ofcanonical' 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 thepossible' 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.