The disk wind in GRS 1915+105 as seen by Insight-HXMT

TL;DR

This study analyzes Insight-HXMT observations of GRS 1915+105, revealing a thermally driven disk wind with significant mass loss, varying ionization, and outflow velocities around 1000 km/s during a soft spectral state.

Contribution

It provides the first detailed analysis of the disk wind properties in GRS 1915+105 using Insight-HXMT data, highlighting the wind's variability and its impact on accretion.

Findings

Detection of highly ionized iron absorption lines indicating disk wind

Wind velocity around 1000 km/s consistent with thermal driving

Mass-loss rate comparable to accretion rate in the inner disk

Abstract

We analyze three observations of GRS 1915+105 in 2017 by Insight-HXMT when the source was in a spectrally soft state. We find strong absorption lines from highly ionized iron, which are due to absorption by disk wind outflowing at a velocity of $\sim$ 1000 km s$^{-1}$ along our line of sight. Two of the three observations show large amplitude oscillation in their light curves and the variation pattern corresponds to state $\kappa$ of GRS 1915+105. From time-averaged and flux-resolved analysis, we find that the variation of the ionization state of the disk wind follows the X-ray continuum on timescales from hundreds seconds to months. The radial location of the disk wind is consistent with thermal driving. The mass-loss rate due to the outflowing wind is comparable to the mass accretion rate in the inner disk, which demonstrates the important role of the disk wind in the disk accretion system.