Disk-Wind Connection During the Heartbeats of GRS 1915+105

TL;DR

This study investigates the connection between the accretion disk and wind in GRS 1915+105 during its heartbeat oscillations, revealing complex wind behavior and disk-wind interactions through joint X-ray observations.

Contribution

It provides new insights into the disk-wind relationship during heartbeat oscillations, including wind velocity components, launch radius, and the role of disk opacity changes.

Findings

Detection of multiple wind velocity components (500-20,000 km/s).

Wind launch radius constrained to less than 6×10^10 cm.

Disk inclination oscillates by approximately 10 degrees.

Abstract

Disk and wind signatures are seen in the soft state of Galactic black holes, while the jet is seen in the hard state. Here we study the disk-wind connection in the $\rho$ class of variability in GRS 1915+105 using a joint NuSTAR-Chandra observation. The source shows 50 sec limit cycle oscillations. By including new information provided by the reflection spectrum, and using phase-resolved spectroscopy, we find that the change in the inner disk inferred from the blackbody emission is not matched by reflection measurements. The latter is almost constant, independent of the continuum model. The two radii are comparable only if the disk temperature color correction factor changes, an effect that could be due to the changing opacity of the disk caused by changes in metal abundances. The disk inclination is similar to that inferred from the jet axis, and oscillates by ~10 deg. The simultaneous Chandra data show the presence of two wind components with velocities between 500-5000 km/s, and possibly two more with velocities reaching 20,000 km/s (~0.06 c). The column densities are ~5e22 cm$^{-2}$. An upper limit to the wind response time of 2 sec is measured, implying a launch radius of <6e10 cm. The changes in wind velocity and absorbed flux require the geometry of the wind to change during the oscillations, constraining the wind to be launched from a distance of 290 - 1300 rg from the black hole. Both datasets support fundamental model predictions in which a bulge originates in the inner disk and moves outward as the instability progresses.