Accretion Flow Dynamics During 1999 Outburst of XTE J1859+226 - Modeling of Broadband Spectra and Constraining the Source Mass

TL;DR

This study models the broadband spectra of XTE J1859+226 during its 1999 outburst to understand accretion flow dynamics, jet ejection, and estimate the black hole's mass using spectral data and the two-component advective flow model.

Contribution

It introduces a comprehensive spectral modeling approach to analyze accretion flow parameters, jet power, and black hole mass during an outburst, integrating observational data with theoretical models.

Findings

Black hole mass estimated between 5.2 and 7.9 solar masses.

Jet power during radio flares is 8-16% of the mass outflow rate.

Spectral modeling aligns with observed accretion rate changes.

Abstract

We examine the dynamical behavior of accretion flow around XTE J1859+226 during the 1999 outburst by analyzing the entire outburst data ($\sim$ 166 days) from RXTE Satellite. Towards this, we study the hysteresis behavior in the hardness intensity diagram (HID) based on the broadband ($3 - 150$ keV) spectral modeling, spectral signature of jet ejection and the evolution of Quasi-periodic Oscillation (QPO) frequencies using the two-component advective flow model around a black hole. We compute the flow parameters, namely Keplerian accretion rate (${\dot m}_d$), sub-Keplerian accretion rate (${\dot m}_h$), shock location ($r_s$) and black hole mass ($M_{bh}$) from the spectral modeling and study their evolution along the q-diagram. Subsequently, the kinetic jet power is computed as $L^{\rm obs}_{\rm jet}\sim 3 - 6 \times 10^{37}$ erg~s$^{-1}$ during one of the observed radio flares which indicates that jet power corresponds to $8-16\%$ mass outflow rate from the disc. This estimate of mass outflow rate is in close agreement with the change in total accretion rate ($\sim 14\%$) required for spectral modeling before and during the flare. Finally, we provide a mass estimate of the source XTE J1859+226 based on the spectral modeling that lies in the range of $5.2 - 7.9 M_{\odot}$ with 90\% confidence.