Title

A Comprehensive Chandra Study of the Disk Wind in the Black Hole Candidate 4U 1630-472

Document Type

Article

Publication Date

11-26-2019

Publication Title

The Astrophysical Journal

Volume

886

Issue

2

First page number:

1

Last page number:

21

Abstract

The mechanisms that drive disk winds are a window into the physical processes that underlie the disk. Stellar-mass black holes are an ideal setting in which to explore these mechanisms, in part because their outbursts span a broad range in mass accretion rate. We performed a spectral analysis of the disk wind found in six Chandra/HETG observations of the black hole candidate 4U 1630−472, covering a range of luminosities over two distinct spectral states. We modeled both wind absorption and extended wind re-emission components using PION, a self-consistent photoionized absorption model. In all but one case, two photoionization zones were required in order to obtain acceptable fits. Two independent constraints on launching radii, obtained via the ionization parameter formalism and the dynamical broadening of the re-emission, helped characterize the geometry of the wind. The innermost wind components ($r\simeq {10}^{2-3}{GM}/{c}^{2}$) tend toward small volume filling factors, high ionization, densities up to $n\simeq {10}^{15-16}\,{\mathrm{cm}}^{-3}$, and outflow velocities of ~0.003c. These small launching radii and large densities require magnetic driving, as they are inconsistent with numerical and analytical treatments of thermally driven winds. Outer wind components ($r\simeq {10}^{5}{GM}/{c}^{2}$) are significantly less ionized and have filling factors near unity. Their larger launching radii, lower densities ($n\simeq {10}^{12}\,{\mathrm{cm}}^{-3}$), and outflow velocities (~0.0007c) are nominally consistent with thermally driven winds. The overall wind structure suggests that these components may also be part of a broader MHD outflow and perhaps better described as magneto-thermal hybrid winds.

Disciplines

Astrophysics and Astronomy | Physical Sciences and Mathematics

Language

English

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