An optically thick disk wind in GRO J1655-40?

Shidatsu, M.; Done, C.; Ueda, Y.

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 $\gtrsim 0.7{L}_{{\rm{Edd}}}$, 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.

Citation

Shidatsu, M., Done, C., & Ueda, Y. (2016). An optically thick disk wind in GRO J1655-40?. Astrophysical Journal, 823(2), Article 159. https://doi.org/10.3847/0004-637x/823/2/159

• Journal Article Type: Article
• Acceptance Date: Apr 14, 2016
• Online Publication Date: Jun 1, 2016
• Publication Date: Jun 1, 2016
• Deposit Date: Sep 7, 2016
• Publicly Available Date: Sep 16, 2016
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 823
• Issue: 2
• Article Number: 159
• DOI: https://doi.org/10.3847/0004-637x/823/2/159
• Public URL: https://durham-repository.worktribe.com/output/1377001