CORONAE AND WINDS FROM IRRADIATED DISKS IN X-RAY BINARIES

Journal Article · Wed Jul 01 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/807/1/107· OSTI ID:22522198

Higginbottom, Nick; Proga, Daniel ^[1]

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1. Department of Physics and Astronomy, University of Nevada, Las Vegas, 4505 S. Maryland Pkwy, Las Vegas, NV 89154-4002 (United States)

X-ray and UV line emission in X-ray binaries (XRBs) can be accounted for by a hot corona. Such a corona forms through irradiation of the outer disk by radiation produced in the inner accretion flow. The same irradiation can produce a strong outflow from the disk at sufficiently large radii. Outflowing gas has been recently detected in several XRBs via blueshifted absorption lines. However, the causal connection between winds produced by irradiation and the blueshifted absorption lines is problematic, particularly in the case of GRO J1655–40. Observations of this source imply wind densities about two orders of magnitude higher than theoretically predicted. This discrepancy does not mean that these “thermal disk winds” cannot explain blueshifted absorption in other systems, nor that they are unimportant as a sink of matter. Motivated by the inevitability of thermal disk winds and wealth of data taken with current observatories such as Chandra, XMM-Newton, and Suzaku, as well as the future AstroH mission, we decided to investigate the requirements to produce very dense winds. Using physical arguments, hydrodynamical simulations, and absorption-line calculations, we found that modification of the heating and cooling rates by a factor of a few results in an increase of the wind density of up to an order of magnitude and the wind velocity by a factor of about two. Therefore, the mass-loss rate from the disk can be one, if not even two, orders of magnitude higher than the accretion rate onto the central object. Such a high mass-loss rate is expected to destabilize the disk and perhaps provides a mechanism for state change.

• OSTI ID: 22522198
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 807; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION SPECTRA
ACCRETION DISKS
BINARY STARS
DENSITY
HEATING
HYDRODYNAMICS
IRRADIATION
MASS TRANSFER
STAR ACCRETION
STELLAR CORONAE
STELLAR WINDS
VELOCITY
X RADIATION