The Constant Inner-Disk Radius of LMC X-3: A Basis for Measuring Black Hole Spin
Abstract
The black-hole binary system LMC X-3 has been observed by virtually every X-ray mission since the inception of X-ray astronomy. Among the persistent sources, LMC X-3 is uniquely both habitually soft and highly variable. Using a fully relativistic accretion-disk model, we analyze hundreds of spectra collected during eight X-ray missions that span 26 years. For a selected sample of 391 RXTE spectra we find that to within ~2 percent the inner radius of the accretion disk is constant over time and unaffected by source variability. Even considering an ensemble of eight X-ray missions, we find consistent values of the radius to within ~4-6 percent. Our results provide strong evidence for the existence of a fixed inner-disk radius. The only reasonable inference is that this radius is closely associated with the general relativistic innermost stable circular orbit (ISCO). Our findings establish a firm foundation for the measurement of black hole spin.
Keywords
Cite
@article{arxiv.1006.5729,
title = {The Constant Inner-Disk Radius of LMC X-3: A Basis for Measuring Black Hole Spin},
author = {James F. Steiner and Jeffrey E. McClintock and Ronald A. Remillard and Lijun Gou and Shin'ya Yamada and Ramesh Narayan},
journal= {arXiv preprint arXiv:1006.5729},
year = {2015}
}
Comments
Accepted for publication in ApJL; 15 manuscript pages, 3 figures