Unraveling the hybrid origins of the X-ray non-thermal emission from IGR J17091-3624

TL;DR

This study uses multi-wavelength observations of IGR J17091-3624's 2022 outburst to explore the origin of its non-thermal X-ray emission, linking variability to jet activity and magnetic fields.

Contribution

It provides new insights into the non-thermal emission mechanisms, suggesting a jet origin and estimating the source distance based on spectral analysis.

Findings

Heartbeat variability correlates with disk temperature changes.

Presence of a power-law component likely from jet synchrotron self-Compton emission.

Estimated distance of 13.7±2.3 kpc for IGR J17091-3624.

Abstract

We present a comprehensive study based on multi-wavelength observations from the NuSTAR, NICER, Swift, Fermi, NEOWISE, and ATCA telescopes during the 2022 outburst of the black hole X-ray binary IGR J17091-3624. Our investigation concentrates on the heartbeat-like variability in the X-ray emission, with the aim of using it as a tool to unravel the origin of the non-thermal emission during the heartbeat state. Through X-ray timing and spectral analysis, we observe that the heartbeat-like variability correlates with changes in the disk temperature, supporting the disk radiation pressure instability scenario. Moreover, in addition to a Comptonization component, our time-averaged and phase-resolved spectroscopy reveal the presence of a power-law component that varies independently from the disk component. Combined with the radio to X-ray spectral energy distribution fitting, our results suggest that the power-law component could originate from synchrotron self-Compton radiation in the jet, which requires a strong magnetic field of about $B = (0.3$-$3.5)\times10^6$ G. Additionally, assuming that IGR J17091-3624 and GRS 1915+105 share the same radio-X-ray correlation coefficient during both the hard and the heartbeat states, we obtain a distance of $13.7\pm2.3$ kpc for IGR J17091-3624.