The Origin of the X-ray and Ultraviolet Emission in Ngc

We present a spectral analysis of a ∼ 30 d, near-continuous observation of the Seyfert 1 galaxy NGC 7469 with RXTE. Daily integrations show strong spectral changes during the observation. Our main result is that we find the X-ray spectral index to be correlated with the UV flux. Furthermore, the broad-band X-ray photon flux is also correlated with the UV continuum. These correlations point towards a model in which the X-rays originate via thermal Comptonization of UV seed photons. Furthermore, the UV is also correlated with the extrapolation of the X-ray power law into the soft X-ray/EUV region. Our data analysis therefore re-opens the possibility the the UV photons and their variability arise from reprocessing, as long as the primary source of heating is photo-electric absorption in the reprocessor, rather than Compton downscattering, A coherent picture of the X-ray/UV variability can therefore be constructed whereby absorption and reprocessing of EUV/soft X-rays in a standard accretion disk produce a variable seed photon distribution which are in turn up-scattered into the X-ray band. We also find a significant correlation between the 2-10 keV flux and the 6.4 keV iron Kα line suggesting that at least some portion of the line originates within ∼ 1 lt day of the X-ray continuum source. Neither the power law photon index nor the Compton reflection component are correlated with the 2-10 keV flux. The latter is not correlated Laboratory for High Energy Astrophysics, Code 660, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 Universities Space Research Association Department of Physics and Astronomy, George Mason University, Fairfax, VA 22030 Department of Astronomy, University of California, Los Angeles, CA 900024 X-ray Astronomy Group, Leicester University, Leicester LE1 7RH, UK Department of Astronomy, Ohio State University, 174 West 18th Avenue, Columbus, OH 43210 University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250