The Demise of the Classical Broad-Line Region in the Luminous Quasar PG 1416−129

Abstract

New observations of the broad-line quasar PG 1416-129 reveal a large decline in its continuum luminosity over the past 10 years. In response to the continuum change, the classical broad component of Hβ has almost completely disappeared (a factor of 10 decrease in flux). In its place there remains a redshifted/redward asymmetric very broad emission line component. The significance of this change is multifold. (1) It confirms the existence of a distinct redshifted very broad line region (VBLR) component that persists after the demise of the broad component and that is frequently observed, along with the broad component, in radio-loud sources. (2) The smaller (decrease by a factor of 2) intensity change in the Hβ very broad component supports the previously advanced idea that the VBLR is physically distinct and likely to arise in an optically thin region close to the central source. (3) The presence of a strong very broad component in the radio-quiet quasar PG 1416-129 reinforces the notion that such population B quasars share similar spectroscopic (and hence geometrical and kinematical) properties to radio-loud sources. (4) AGNs can show broad, very broad, or both line components simultaneously, making statistical comparisons of source profile widths difficult. (5) The interpretation, in reverberation studies, of the presence or lack of correlated response in broad-line wings will be affected by this composite BLR/VBLR structure.