@inproceedings{b47b29f82ec74da995e17764dfc6cfd1,
title = "Suzaku observations of 4U 1957+11: The most rapidly spinning black hole in the galaxy?",
abstract = "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 fromdisk-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 ⊙, 10 kpc), the dimensionless spin parameter a*≡Jc/GM 2≳0.9. Higher masses and farther distances yield a* ≈1. Low spin cannot be recovered unless 4U 1957+11 is a low mass black hole that is at the unusually large distance of ≳ 40 kpc.",
keywords = "accretion, accretion disks, black hole physics, X-rays:binaries",
author = "Nowak, \{Michael A.\} and J{\"o}rn Wilms and Katja Pottschmidt and Norbert Schulz and Jon Miller and Dipankar Maitra",
year = "2012",
doi = "10.1063/1.3696149",
language = "English",
isbn = "9780735410107",
series = "AIP Conference Proceedings",
pages = "48--51",
booktitle = "SUZAKU 2011 - Exploring the X-Ray Universe",
note = "Suzaku 2011: Exploring the X-Ray Universe: Suzaku and Beyond ; Conference date: 20-07-2011 Through 22-07-2011",
}