# 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.

## Key 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.