Document Type

Article

Publication Date

4-27-2020

Publication Title

The Astrophysical Journal

Volume

893

Issue

2

First page number:

1

Last page number:

15

Abstract

Chandra obtained two High Energy Transmission Grating spectra of the stellar-mass black hole GRO J1655−40 during its 2005 outburst, revealing a rich and complex disk wind. Soon after its launch, the Neil Gehrels Swift Observatory began monitoring the same outburst. Some X-ray Telescope (XRT) observations were obtained in a mode that makes it impossible to remove strong Mn calibration lines, so the Fe Kα line region in the spectra was previously neglected. However, these lines enable a precise calibration of the energy scale, facilitating studies of the absorption-dominated disk wind and its velocity shifts. Here we present fits to 15 Swift/XRT spectra, revealing variability and evolution in the outflow. The data strongly point to a magnetically driven disk wind: both the higher-velocity (e.g., ) and lower-velocity (e.g., ) wind components are typically much faster than is possible for thermally driven outflows (), and photoionization modeling yields absorption radii that are two orders of magnitude below the Compton radius that defines the typical inner extent of thermal winds. Moreover, correlations between key wind parameters yield an average absorption measure distribution that is consistent with magnetohydrodynamic wind models. We discuss our results in terms of recent observational and theoretical studies of black hole accretion disks and outflows, as well as future prospects.

Keywords

Black holes; Compact objects; Stellar accretion disks

Disciplines

Cosmology, Relativity, and Gravity | Stars, Interstellar Medium and the Galaxy

File Format

pdf

File Size

1.742 KB

Language

English

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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