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[20.06] Coronae and Jet Properties of the Black Hole Candidates Cyg X-1 and GX339-4 Over Many Years and Many Decades in Eddington Flux

M.A. Nowak (MIT), J. Wilms (University of Warwick), K. Pottschmidt (MPE/ISDC), G.G. Pooley (University of Cambridge)

Over the past seven years, our group has used the Rossi X-ray Timing Explorer to monitor the canonical black hole candidates Cyg X-1 and GX339-4. Often these observations have been performed simultaneously in radio, and occasionally optical, wavebands. The Cyg X-1 campaign represents >250 observations performed over approximately a decade in 2-200 keV flux, whereas the GX339-4 campaign represents >20 observations performed over 4 decades in 2-200 keV flux. We have previously published phenomenological spectral fits (e.g., exponentially cutoff, reflected power laws with simple gaussian lines) to the Cyg X-1 data, and have further correlated the resulting spectral fit parameters with variability information (e.g., characteristic time scales from Fourier power spectra, time lags between soft and hard variability, etc.). For the GX339-4 campaign we have additionally considered physically motivated, sophisticated Comptonization models, and correlated those spectral fit parameters with timing information. Here, we reverse this approach. We first present phenomenological spectral models - fitting the full radio to X-ray spectrum in detector space (i.e., not `unfolded' data) - to describe the simultaneous radio/X-ray spectra. We use these phenomenological spectral fits to comment on the `universal' correlation between radio and X-ray flux in the hard state. We further discuss the `IR coincidence' that postulates that the flat radio spectrum extrapolated forward in energy, and the underlying hard X-ray power law extrapolated backwards in energy, meet at a spectral break in the IR. We use these results to comment on pure synchrotron models for the observed hard state X-ray spectra. We then consider sophisticated Comptonization models fit to the entire Cyg X-1 campaign. We contrast the correlation between coronal hardness and reflection fraction to the purely phenomenological `Gamma-Delta Gamma' correlation obtained from (frighteningly successful) broken power law fits. We then outline some of our thoughts about what we see as the likely future of hard state spectral models: the unification of corona and jet models.

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Bulletin of the American Astronomical Society, 36 #3
© 2004. The American Astronomical Soceity.