Nowak MA, Wilms J, Pottschmidt K, Schulz N, Miller J, Maitra D (2012)
Publication Status: Published
Publication Type: Conference contribution
Publication year: 2012
Book Volume: 1427
DOI: 10.1063/1.3696149
We present three Suzaku observations of the black hole candidate 4U 1957+11-a source that exhibits some of the simplest and cleanest examples of soft, disk-dominated spectra. 4U 1957+11 also presents among the highest peak temperatures found from disk-dominated spectra. Such temperatures may be associated with rapid black hole spin. The 4U 1957+11 spectra also require a very low normalization, which can be explained by a combination of small inner disk radius and a large distance (> 10 kpc) which places 4U 1957+11 well into the Galactic halo. We perform joint fits to the Suzaku spectra with relativistic disk models. Assuming a low mass black hole and the nearest distance (3M(circle dot), 10 kpc), the dimensionless spin parameter a* = Jc/GM(2) greater than or similar to 0.9. Higher masses and farther distances yield a* approximate to 1. Low spin cannot be recovered unless 4U 1957+11 is a low mass black hole that is at the unusually large distance of greater than or similar to 40 kpc.
APA:
Nowak, M.A., Wilms, J., Pottschmidt, K., Schulz, N., Miller, J., & Maitra, D. (2012). Suzaku Observations of 4U 1957+11: The Most Rapidly Spinning Black Hole in the Galaxy?.
MLA:
Nowak, Michael A., et al. "Suzaku Observations of 4U 1957+11: The Most Rapidly Spinning Black Hole in the Galaxy?" 2012.
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