More Evidence for the Intermediate Broad Line Region of the Mapped AGN PG 0052+251

TL;DR

This study provides evidence for an intermediate broad line region in the AGN PG 0052+251 by analyzing line profiles, time lags, and correlations, supporting the existence of multiple broad line regions.

Contribution

It introduces a two-component model for broad emission lines and confirms the intermediate BLR through line analysis and lag measurements, advancing understanding of AGN structure.

Findings

Different time lags for inner and intermediate components

Distinct correlation patterns between line width and flux

Support for the existence of an intermediate broad line region

Abstract

In the manuscript, the properties of the proposed intermediate BLR are checked for the mapped AGN PG 0052+251. With the considerations of the apparent effects of the broad He {\sc ii} line on the observed broad H$\beta$ profile, the line parameters (especially the line width and the line flux) of the observed broad H$\alpha$ and the broad H$\beta$ are carefully determined. Based on the measured line parameters, the model with two broad components applied for each observed broad balmer line is preferred, and then confirmed by the calculated much different time lags for the inner/intermediate broad components and the corresponding virial BH masses ratio determined by the properties of the inner and the intermediate broad components. Then, the correlation between the broad line width and the broad line flux is checked for the two broad components: one clearly strong negative correlation for the inner broad component, but one positive correlation for the intermediate broad component. The different correlations for the two broad components strongly support the intermediate BLR of PG0052+251.