# Study of the long-term evolution of the accretion dynamics of GX 339-4

## TL;DR

This study analyzes the long-term accretion dynamics of GX 339-4 over multiple outbursts, revealing the role of irradiation-induced instabilities and modeling spectral evolution with a two-component accretion disc to understand long rising times.

## Contribution

It introduces a unified model explaining long rising times in outbursts and discusses the physical differences in outbursts with shorter rising times.

## Key findings

- Second peaks due to irradiation-induced instabilities
- Long rising time of ~90 days for all four outbursts
- Proposed mathematical model for accretion parameter evolution

## Abstract

We study the dynamical behaviour of the galactic black hole source GX 339-4 during 2002-2011 outbursts using RXTE, Swift(XRT), XMM-Newton(PN) archival data. We present the spectral evolution of the source using four outbursts data and discuss their similarities/differences between outbursts. We infer that the second peak in 2002/03 and 2004/05 outbursts can be due to a second instant of triggered instability in the accretion disc due to irradiation from the central X-ray source after peak-I. This propagates in viscous time scale and takes ~80-90 days after peak-I to produce peak-II. This unifies all four outbursts having a long rising time of ~90 days. The dynamical evolution of accretion parameters have been studied by modeling the individual observed spectrum with two-component accretion disc model where a Keplerian accretion disc produces the soft photons and the hard part of the spectrum originates from a hot sub-Keplerian central corona. A generic mathematical model has been proposed to understand the evolution of accretion parameters for sources like GX 339-4 which have longer rising time. Also, the possible differences of physical scenario for outbursts with shorter rising time are also discussed.