The high-energy emission from GX 339-4 as seen with INTEGRAL and XMM-Newton

TL;DR

This study analyzes the spectral evolution of the microquasar GX 339-4 during an outburst using INTEGRAL and XMM-Newton, revealing changes in coronal properties and the necessity of a non-thermal component across different states.

Contribution

It provides new insights into the evolution of the corona's physical properties and geometry during state transitions in GX 339-4 using joint spectral modeling.

Findings

Detection of spectral hardening and skewed Fe line during intermediate state

Evidence for a non-thermal component in all spectral states

Transition from a compact corona to disappearance and re-appearance

Abstract

GX 339--4 is a well-known microquasar. In this contribution we show the obtained results with the INTEGRAL and XMM-Newton observatories of the outburst undertaken on 2007. The observations cover spectral evolution from the hard, soft intermediate states to the high/soft state. Spectral hardening correlated with the appearance of an skewed Fe line is detected during one of the observations during the soft intermediate state. In all spectral states joint XMM/EPIC-pn, JEM-X, ISGRI and SPI data were fit with the hybrid thermal/non-thermal Comptonization model (EQPAIR). With this model a non-thermal component seems to be required by the data in all the observations. Our results imply evolution in the coronal properties, the most important one being the transition from a compact corona in the first observation to the disappearance of coronal material in the second and re-appearance in the third. We discuss the results obtained in the context of possible physical scenarios for the origin and geometry of the corona and its relation to black hole states.