The "red shelf" of the Hβ line in the Seyfert 1 galaxies RXS J01177+3637 and HS 0328+05

Abstract

A few Seyfert 1s have a Hβ profile with a red wing usually called the "red shelf". The most popular interpretation of this feature is that it is due to broad redshifted lines of Hβ and [O III]λλ4959, 5007; we have observed two Seyfert 1s displaying a "red shelf" and showed that in these two objects the main contributor is most probably the He I λλ4922, 5016 lines having the velocity and width of the broad Hβ component. There is no evidence for the presence of a broad redshifted component of Hβ or [O III] in any of these two objects.