Characterization of GX 339-4 outburst of 2010-11: analysis by xspec using two component advective flow model

TL;DR

This study analyzes the spectral evolution of GX 339-4 during its 2010-11 outburst using the TCAF model in XSPEC, revealing how accretion parameters and QPOs change across different spectral states.

Contribution

First application of the TCAF model in XSPEC to fit GX 339-4 outburst spectra, providing detailed accretion flow parameters and their variation during the outburst.

Findings

QPO frequencies correlate with ARR variations.

ARR peaks at state transition points.

Flow components are independent, evidenced by ARR variability.

Abstract

We study spectral properties of GX 339-4 during its 2010-11 outburst with Two Component Advective Flow (TCAF) model after its inclusion in XSPEC as a table model. We compare results fitted by TCAF model with combined disk black body and power-law model. For a spectral fit, we use 2.5-25 keV spectral data of the PCA instrument onboard RXTE satellite. From our fit, accretion flow parameters such as Keplerian (disk) rate, sub-Keplerian (halo) rate, location and strength of shock are extracted. We quantify how the disk and the halo rates vary during the entire outburst. We study how the halo to disk accretion rate ratio (ARR), quasi-periodic oscillations (QPOs), shock locations and its strength vary when the system passes through hard, hard-intermediate, soft-intermediate, and soft states. We find pieces of evidence of monotonically increasing and decreasing nature of QPO frequencies depending on the variation of ARR during rising and declining phases. Interestingly, on days of transition from hard state to hard-intermediate spectral state (during the rising phase) or vice-versa (during decline phase), ARR is observed to be locally maximum. Non-constancy of ARR while obtaining reasonable fits points to the presence of two independent components in the flow.