SIMBAD references

We test the ``reprocessing paradigm'' of optical-UV active galactic nucleus (AGN) variability, according to which the variations in this wavelength range are driven by a variable X-ray component, by detailed modeling of the correlated X-ray-optical (3590 and 5510 Å) variability of the recent multiwavelength campaign of NGC 3516. To this end we produce model optical light curves by convolving the observed X-ray flux with the response function of an infinite, thin accretion disk, illuminated by a pointlike X-ray source located at a given height h_X above the compact object (the lamppost model). We also produce the ionized X-ray reflection and Fe Kα line spectra that result from the reprocessing of the same X-rays on the disk surface. Then we compare the properties of the model light curves (amplitude, morphology, lags) as well as those of the Fe Kα line profiles to those observed. Our calculations improve on those of similar past treatments by including the effects of an X-ray-heated ionized layer in hydrostatic equilibrium on its surface, which greatly affects its X-ray timing and spectral properties. The results of our calculations do not provide a clear-cut picture that would either support or refute the reprocessing paradigm: despite the large (≃50%) amplitude excursions of the X-ray flux, the model optical light curves exhibit variability amplitudes of only 3%-4% and vary in synchrony in the two bands, in agreement with observations. However, the model light curves, when viewed in detail, do not have a direct correspondence to those observed. Futhermore, while the observed intraband synchrony generally points toward smaller values for the black hole mass (M=10⁷ M_☉), the X-ray Fe Kα line, X-ray reflection, and optical-UV spectra seem to favor larger mass values (M=10⁸ M_☉). Generally, no combination of the model parameters seems to produce agreement with the ensemble of the constraints imposed by optical/UV/X-ray spectral and timing observations; we are thus led to believe that the simplest version of the lamppost model geometry is inconsistent with the NGC 3516 observations.