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The Accretion Disk Wind in the Black Hole GRS 1915 + 105We report on a 120 kiloseconds Chandra/HETG spectrum of the black hole GRS 1915+105. The observation was made during an extended and bright soft state in 2015 June. An extremely rich disk wind absorption spectrum is detected, similar to that observed at lower sensitivity in 2007. The very high resolution of the third-order spectrum reveals four components to the disk wind in the Fe K band alone; the fastest has a blueshift of v = 0.03 c (velocity equals 0.03 the speed of light). Broadened reemission from the wind is also detected in the first-order spectrum, giving rise to clear accretion disk P Cygni profiles. Dynamical modeling of the re-emission spectrum gives wind launching radii of r approximately equal to 10 (sup 2-4) GM (Gravitational constant times Mass) divided by c (sup 2) (the speed of light squared). Wind density values of n approximately equal to 10 (sup 13-16) per cubic centimeter are then required by the ionization parameter formalism. The small launching radii, high density values, and inferred high mass outflow rates signal a role for magnetic driving. With simple, reasonable assumptions, the wind properties constrain the magnitude of the emergent magnetic field to be B approximately equal to 10 (sup 3-4) G (Gravitational constant) if the wind is driven via magnetohydrodynamic (MHD) pressure from within the disk and B approximately equal to 10 (sup 4-5) G (Gravitational constant) if the wind is driven by magnetocentrifugal acceleration. The MHD estimates are below upper limits predicted by the canonical alpha-disk model. We discuss these results in terms of fundamental disk physics and black hole accretion modes.
Document ID
Document Type
Reprint (Version printed in journal)
Miller, J.M. (Michigan Univ. Ann Arbor, MI, United States)
Raymond, J. (Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Fabian, A. C. (Cambridge Univ. Cambridge, United Kingdom)
Gallo, E. (Michigan Univ. Ann Arbor, MI, United States)
Kaastra, J. (SRON Space Research Organization Utrecht, Netherlands)
Kallman, T. (NASA Goddard Space Flight Center Greenbelt, MD United States)
King, A. L. (Stanford Univ. Stanford, CA, United States)
Proga, D. (Nevada Univ. Las Vegas, NV, United States)
Reynolds, C. S. (Maryland Univ. College Park, MD, United States)
Zoghbi, A. (Michigan Univ. Ann Arbor, MI, United States)
Date Acquired
March 29, 2017
Publication Date
April 7, 2016
Publication Information
Publication: The Astrophysical Journal Letters
Volume: 821
Issue: 1
ISSN: 2041-8205
Subject Category
Report/Patent Number
Distribution Limits
accretion disks