Lyman alpha fluxes of Seyfert galaxies and low-redshift quasars.

Abstract

The International Ultraviolet Explorer (IUE) was used to measure Ly-alpha fluxes for 13 type 1 Seyferts, one type 2 Seyfert, and one low-redshift quasar. The observed Ly-alpha/H-beta ratio is typically 5 for the type 1 Seyfert galaxies but is 20 for the single type 2 Seyfert. In the Ly-alpha/H-beta versus H-alpha/H-beta diagram, the observations do not preferentially fall along any characteristic reddening line, indicating a considerable range of intrinsic line ratios. Much of the low Ly-alpha/H-beta ratio is intrinsic to the broad-line region; external dust plays a significant role in only a few objects. For type 1 Seyferts and low-redshift QSOs, the intrinsic line ratios are limited to Ly-alpha/H-beta less than 20, and H-alpha/H-beta greater than approximately 2.8.