The intrinsic Baldwin effect in broad Balmer lines of six long-term monitored AGNs

Abstract

We investigate the intrinsic Baldwin effect (Beff) of the broad Hα and Hβ emission lines for six Type 1 active galactic nuclei (AGNs) with different broad line characteristics: two Seyfert 1 (NGC 4151 and NGC 5548), two AGNs with double-peaked broad line profiles (3C 390.3 and Arp 102B), one narrow line Seyfert 1 (Ark 564), and one high-luminosity quasar with highly red asymmetric broad line profiles (E1821+643). We find that a significant intrinsic Beff was present in all Type 1 AGNs in our sample. Moreover, we do not see strong differences in intrinsic Beff slopes in different types of AGNs, which probably have different physical properties such as inclination, broad line region (BLR) geometry, or accretion rate. Additionally, we find that the intrinsic Beff was not connected with the global Beff, which, instead, could not be detected in the broad Hα or Hβ emission lines. In the case of NGC 4151, the detected variation of the Beff slope could be due to the change in the site of line formation in the BLR. Finally, the intrinsic Beff might be caused by the additional optical continuum component that is not part of the ionization continuum.