| Abstract: | AGN are characterized by broad emission lines. The lines show similar properties from the lowest luminosity (10^39 erg/s) to the highest luminosity (10^47 erg/s) AGN. What produces this similarity over such a vast range of 10^8 in luminosity? Photoionization is inevitably associated with momentum transfer to the photoionized gas. I will describe how this mechanism can explain the universality of the properties of the Broad Line Region (BLR) in AGN. Applying this mechanism to broad absorption line (BAL) gas implies universal ionic columns that are independent of distance from the continuum source. I will discuss how the universal ionic columns allow to place the BAL outflows at the BLR, and present observational evidence supporting this scenario. |
