SUZAKU Observation of the Black Hole Binary 4U 1630-47 in the Very High State

Hori, T.; Ueda, Y.; Shidatsu, M.; Kawamuro, T.; Kubota, A.; Done, C.; Nakahira, S.; Tsumura, K.; Shirahata, M.; Nagayama, T.

Abstract

We report the results from an X-ray and near-infrared observation of the Galactic black hole binary 4U 1630-47 in the very high state (VHS), performed with Suzaku and the Infrared Survey Facility around the peak of the 2012 September-October outburst. The X-ray spectrum is approximated by a steep power law, with photon index of 3.2, identifying the source as being in the VHS. A more detailed fit shows that the X-ray continuum is well described by a multicolor disk, together with thermal and nonthermal Comptonization. The inner disk appears slightly truncated by comparison with a previous high/soft state of this source, even taking into account energetic coupling between the disk and corona, although there are uncertainties due to the dust-scattering correction. The near-infrared fluxes are higher than the extrapolated disk model, showing that there is a contribution from irradiation in the outer disk and/or the companion star at these wavelengths. Our X-ray spectra do not show the Doppler-shifted iron emission lines indicating a baryonic jet that were seen four days previously in an XMM-Newton observation, despite the source being in a similar state. There are also no significant absorption lines from highly ionized iron lines as are seen in the previous high/soft state data. We show that the increased source luminosity is not enough on its own to make the wind so highly ionized as to be undetectable. This shows that the disk wind has changed in terms of its launch radius and/or density compared to the high/soft state.

Citation

Hori, T., Ueda, Y., Shidatsu, M., Kawamuro, T., Kubota, A., Done, C., …Nagayama, T. (2014). SUZAKU Observation of the Black Hole Binary 4U 1630-47 in the Very High State. Astrophysical Journal, 790(1), Article 20. https://doi.org/10.1088/0004-637x/790/1/20

• Journal Article Type: Article
• Publication Date: Jul 20, 2014
• Deposit Date: Mar 16, 2016
• Publicly Available Date: Jun 22, 2016
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 790
• Issue: 1
• Article Number: 20
• DOI: https://doi.org/10.1088/0004-637x/790/1/20
• Public URL: https://durham-repository.worktribe.com/output/1409066
• Related Public URLs: http://adsabs.harvard.edu/abs/2014ApJ...790...20H