Evidence for a black-hole in the X-ray transient XTE J1859+226
Abstract
We present the results of time-resolved optical photometry and spectroscopy of the X-ray transient XTE J1859+226 (V406 Vul). Photometric observations taken during 2000 and 2008 reveals the presence of the secondary star's ellipsoidal modulation. Further photometry obtained in 2010 shows the system ~1 mag brighter than its quiescence level and the ellipsoidal modulation diluted by strong flaring activity. Spectroscopic data obtained with the 10.4-m GTC in 2010 reveals radial velocity variations of ~500 km/s over 3 h. A simultaneous fit to the photometry and spectroscopy using sinusoids to represent the secondary star's ellipsoidal and radial velocity variations, yields an orbital period of 6.58+-0.05 h and a secondary star's radial velocity semi-amplitude of K_2= 541+-70 km/s. The implied mass function is f(M)=4.5+-0.6 Msun, significantly lower than previously reported but consistent with the presence of a black hole in XTE J1859+226. The lack of eclipses sets an upper limit to the inclination of 70 degrees which yields a lower limit to the black hole mass of 5.42 Msun.
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Cite
@article{arxiv.1102.0654,
title = {Evidence for a black-hole in the X-ray transient XTE J1859+226},
author = {J. M. Corral-Santana and J. Casares and T. Shahbaz and C. Zurita and I. G. Martínez-Pais and P. Rodríguez-Gil},
journal= {arXiv preprint arXiv:1102.0654},
year = {2015}
}
Comments
Accepted for publication in MNRAS. Contains 5 pages and 4 figures