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The Reflection Component from Cygnus X-1 in the Soft State Measured by NuSTAR and Suzaku

Tomsick, John A. and Nowak, Michael A. and Parker, Michael and Miller, Jon M. and Fabian, Andy C. and Harrison, Fiona A. and Bachetti, Matteo and Barret, Didier and Boggs, Steven E. and Christensen, Finn E. and Craig, William W. and Forster, Karl and Fürst, Felix and Grefenstette, Brian W. and Hailey, Charles J. and King, Ashley L. and Madsen, Kristin K. and Natalucci, Lorenzo and Pottschmidt, Katja and Ross, Randy R. and Stern, Daniel and Walton, Dominic J. and Wilms, Jörn and Zhang, William W. (2014) The Reflection Component from Cygnus X-1 in the Soft State Measured by NuSTAR and Suzaku. Astrophysical Journal, 780 (1). Art. No. 78. ISSN 0004-637X. doi:10.1088/0004-637X/780/1/78.

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The black hole binary Cygnus X-1 was observed in late 2012 with the Nuclear Spectroscopic Telescope Array (NuSTAR) and Suzaku, providing spectral coverage over the ~1-300 keV range. The source was in the soft state with a multi-temperature blackbody, power law, and reflection components along with absorption from highly ionized material in the system. The high throughput of NuSTAR allows for a very high quality measurement of the complex iron line region as well as the rest of the reflection component. The iron line is clearly broadened and is well described by a relativistic blurring model, providing an opportunity to constrain the black hole spin. Although the spin constraint depends somewhat on which continuum model is used, we obtain ɑ_* > 0.83 for all models that provide a good description of the spectrum. However, none of our spectral fits give a disk inclination that is consistent with the most recently reported binary values for Cyg X-1. This may indicate that there is a >13° misalignment between the orbital plane and the inner accretion disk (i.e., a warped accretion disk) or that there is missing physics in the spectral models.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Tomsick, John A.0000-0001-5506-9855
Nowak, Michael A.0000-0001-6923-1315
Fabian, Andy C.0000-0002-9378-4072
Harrison, Fiona A.0000-0003-2992-8024
Bachetti, Matteo0000-0002-4576-9337
Barret, Didier0000-0002-0393-9190
Boggs, Steven E.0000-0001-9567-4224
Christensen, Finn E.0000-0001-5679-1946
Forster, Karl0000-0001-5800-5531
Fürst, Felix0000-0003-0388-0560
Grefenstette, Brian W.0000-0002-1984-2932
Madsen, Kristin K.0000-0003-1252-4891
Natalucci, Lorenzo0000-0002-6601-9543
Pottschmidt, Katja0000-0002-4656-6881
Stern, Daniel0000-0003-2686-9241
Walton, Dominic J.0000-0001-5819-3552
Wilms, Jörn0000-0003-2065-5410
Zhang, William W.0000-0002-1426-9698
Additional Information:© 2014 American Astronomical Society. Received 2013 September 3; accepted 2013 October 14; published 2013 December 13. This work was supported under NASA Contract No. NNG08FD60C and made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software, and Calibration teams for support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). J.A.T. acknowledges partial support from NASA Astrophysics Data Analysis Program grant NNX13AE98G. L.N. wishes to acknowledge the Italian Space Agency (ASI) for financial support by ASI/INAF grant I/037/12/0-011/13. J.A.T. thanks L. Brenneman, G. Matt, and D. Ballantyne for useful discussions about reflection modeling. This work made use of IDL software written by N. Barrière for rebinning the NuSTAR spectra. This research has made use of the MAXI data provided by RIKEN, JAXA, and the MAXI team.
Group:NuSTAR, Space Radiation Laboratory
Funding AgencyGrant Number
Agenzia Spaziale Italiana (ASI)I/037/12/0-011/13
Subject Keywords:accretion, accretion disks; black hole physics; stars: individual (Cygnus X-1); X-rays: general; X-rays: stars
Issue or Number:1
Record Number:CaltechAUTHORS:20140131-084009659
Persistent URL:
Official Citation:The Reflection Component from Cygnus X-1 in the Soft State Measured by NuSTAR and Suzaku John A. Tomsick et al. 2014 ApJ 780 78
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43600
Deposited By: Ruth Sustaita
Deposited On:31 Jan 2014 17:05
Last Modified:10 Nov 2021 16:40

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