We have conducted optical and X-ray simultaneous observations of SWIFT J1753.5-0127 with RXTE and ULTRACAM, while the system persisted in its relatively bright low/hard state. In the cross-correlation function (CCF), we find that the optical leads the X-rays by a few seconds with a broad negative peak, and has a smaller positive peak at positive lags. This is markedly different from what was seen for the similarly interesting system XTE J1118+480, and the first time such a correlation function has been so clearly measured. Furthermore, there appears to be a significant variation of the correlation with X-ray energy. We suggest a physical scenario for its origin.
Cite
@article{arxiv.0806.2530,
title = {SWIFT J1753.5-0127: a surprising optical/X-ray cross-correlation function},
author = {Martin Durant and Poshak Gandhi and Tariq Shahbaz and Andy Fabian and Jon Miller and V. S. Dhillon and Tom R. Marsh},
journal= {arXiv preprint arXiv:0806.2530},
year = {2009}
}
Comments
10 page manuscript. Accepted for publication in ApJL