Strong Response of the very broad h$\beta$ Emission Line in Luminous Radio-Quite Quasar pg1416-129

Abstract

We report new spectroscopic observations performed in 2010 and 2011 for luminous radio-quite quasar PG 1416-129. Our new spectra with high quality cover both H$\beta$ and H$\alpha$ regions, and show negligible line profile variation within a timescale of one year. The two spectra allow us to study the variability of the Balmer line profile by comparing the spectra with the previous ones taken at 10 and 20 years ago. By decomposing the broad Balmer emission lines into two Gaussian profiles, our spectral analysis suggests a strong response to the continuum level for the very broad component, and significant variations in both bulk blueshift velocity/FWHM and flux for the broad component. The new observations additionally indicate flat Balmer decrements (i.e., too strong H$\beta$ emission) at the line wings, which is hard to be reproduced by recent optically thin models. With these observations we argue that a separate inner optically thin emission-line region might not be necessary in the object to reproduce the observed line profiles.