Because binary X-ray sources are strong emitters over a broad range of the electromagnetic spectrum, with each part of the spectrum contributing distinct and often time-variable information, attempts to understand these systems by concentrating on information from a limited wavelength range may lead to contradictory and misleading conclusions. The spectral energy distribution of stars and AGN provide unique information on the energy balance of the systems studied and have been used to great benefit to further our understanding of their characteristics and evolution. Hitherto the SEDs of X-ray binaries have not been systematically analyzed because the extreme variability of XRBs require simultaneous observations across the spectrum, and this has been accomplished for only a handful of objects (e.g. Herx-1, Sco X-1, Cyg X-3). Simultaneous multiwavelength studies of the few sources that have been examined in this way have been remarkably successful in explaining X-ray, ultraviolet (UV), and optical observations and resulted in improved physical constraints on the systems, a new understanding of the dependence of mass accretion rate on X-ray state, as well as insights on the time-dependent relationship between disk structure and mass-transfer rate, (e.g., Vrtilek~\etal~1990,1991,2001; Hasinger~\etal~1990; McClintock~\etal~2001; Fuchs~\etal~2003; Homan~\etal~2005)

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Broadband energy spectra of a selection of black hole and neutron star binaries showing variability between sources (ATCA and RXTE values are from a survey conducted by the Jets/Disk Consortium in June of 2006; values for Sco X-1 are from Wachter~\etal~2006).

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This page last updated April 28 2009