EMISSION-LINE AND ULTRAVIOLET TO X-RAY CONTINUUM CORRELATIONS - CONSTRAINTS ON THE ANISOTROPY OF THE IONIZING CONTINUUM IN ACTIVE GALACTIC NUCLEI

Anisotropic emission of the ionizing continuum is a general prediction of accretion disk models. In this paper, we present the results of co rrelation analysis of the UV emission line and UV to X-ray continuum p roperties for a large sample of broad emission line AGNs observed with ROSAT, IUE, and HST. We find strong correlations between the C IV/Ly alpha ratio, the equivalent width of C Iv, and the UV to soft X-ray sp ectral slope. The results are in good agreement with the photoionizati on calculation, suggesting that the overall ionizing continuum can wel l match the observed UV to soft X-ray spectrum. These results are cons istent with the assumption of an isotropic ionizing continuum shape. O ur analysis suggests a small range for the ''big blue bump'' cutoff en ergy for the objects in this sample, consistent with the similar resul ts of Laor et al. and Waiter & Fink based on continuum properties. The mean UV to X-ray spectral slope is similar to the soft X-ray spectral slope. This similarity also holds for radio-loud and radio-quiet obje cts separately. This suggests that the two might be drawn from the sam e distribution. The two spectral slopes, are only weakly correlated. T he UV to X-ray spectral index is correlated with absolute optical magn itude. This result confirms the earlier suggestion that the ionizing c ontinua are softer for higher luminosity objects.