An Optically Thick Disk Wind in GRO J1655-40?
Abstract
We revisited the unusual wind in GRO J1655-40, detected with Chandra in 2005 April, using long-term Rossi X-ray Timing Explorer X-ray data and simultaneous optical/near-infrared photometric data. This wind is the most convincing case for magnetic driving in black hole binaries, as it has an inferred launch radius that is a factor of 10 smaller than the thermal wind prediction. However, the optical and near-infrared (OIR) fluxes monotonically increase around the Chandra observation, whereas the X-ray flux monotonically decreases from 10 days beforehand. Yet the optical and near-infrared fluxes are from the outer, irradiated disk, so for them to increase implies that the X-rays likewise increased. We applied a new irradiated disk model to the multi-wavelength spectral energy distributions. Fitting the OIR fluxes, we estimated the intrinsic luminosity at the Chandra epoch was ≳ 0.7{L}{{Edd}}, which is more than one order of magnitude larger than the observed X-ray luminosity. These results could be explained if a Compton-thick, almost completely ionized gas was present in the wind and strong scattering reduced the apparent X-ray luminosity. The effects of scattering in the wind should then be taken into account for discussion of the wind-driving mechanism. Radiation pressure and Compton heating may also contribute to powering the wind at this high luminosity.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2016
- DOI:
- 10.3847/0004-637X/823/2/159
- arXiv:
- arXiv:1604.04346
- Bibcode:
- 2016ApJ...823..159S
- Keywords:
-
- accretion;
- accretion disks;
- black hole physics;
- X-rays: binaries;
- X-rays: individual: GRO J1655–40;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 12 pages, 6 figures, accepted for publication in ApJ