X-Ray Eclipse Time Delays in 4U2129+47
Abstract
4U 2129+47 was discovered in the early 80's and classified as an accretion disk corona source due to its broad and partial X-ray eclipses. The 5.24 hr binary orbital period was inferred from the X-ray and optical light curve modulation, implying a late K or M spectral type companion star. The source entered a low state in 1983, during which the optical modulation disappeared and an F8 IV star was revealed, suggesting that 4U 2129+47 might be part of a triple system. The nature of 4U 2129+47 has since been investigated, but no definitive conclusion has been reached. Here, we present timing and spectral analyses of two XMM-Newton observations of this source, carried out in May and June, 2005. We find evidence for a delay between two mid-eclipse epochs measured ~22 days apart, and we show that this delay can be naturally explained as being due to the orbital motion of the binary 4U 2129+47 around the center of mass of a triple system. This result thus provides further support in favor of the triple nature of 4U 2129+47.
Cite
@article{arxiv.0709.4366,
title = {X-Ray Eclipse Time Delays in 4U2129+47},
author = {E. Bozzo and M. Falanga and A. Papitto and L. Stella and R. Perna and D. Lazzati and G. Israel and S. Campana and V. Mangano and T. Di Salvo and L. Burderi},
journal= {arXiv preprint arXiv:0709.4366},
year = {2009}
}
Comments
6 pages, 5 figures, accepted by A&A