We present XMM-Newton observations of the black hole X-ray nova V404 Cyg in quiescence. Its quiescent spectrum can be best fitted by a simple power law with slope Γ ∼ 2. The spectra are consistent with that expected for the advection-dominated accretion flow (ADAF). V404 Cyg was roughly equal in luminosity compared to the previous observation of Chandra. We see variability of a factor of 4 during the observation. We find no evidence for the presence of fluorescent or H-like/He-like iron emission, with upper limits of 52 and 110 eV, respectively. The limit on the fluorescent emission is improved by a factor of 15 over the previous estimate, and the restriction on H-like/He-like emission is lower than predicted from models by a factor of roughly 2. © 2007. The American Astronomical Society. All rights reserved.
Publication Source (Journal or Book title)
Bradley, C., Hynes, R., Kong, A., Haswell, C., Casares, J., & Gallo, E. (2007). The spectrum of the black hole X-ray nova V404 cygni in quiescence as measured by XMM-Newton. Astrophysical Journal, 667 (1 I), 427-432. https://doi.org/10.1086/520323