The Covering Factor of Warm Dust in Weak Emission-Line Active Galactic Nuclei

TL;DR

This study analyzes the spectral energy distributions of 73 weak emission-line AGNs, finding their warm dust covering factors similar to normal AGNs, and discusses implications for their evolutionary stage rather than accretion rates.

Contribution

It provides the first comprehensive analysis of the warm dust covering factor in WLAGNs, supporting an evolutionary scenario over accretion-based explanations.

Findings

WLAGNs have similar warm dust covering factors as normal AGNs.

No significant difference in covering factor between WLAGNs and normal AGNs.

Results favor an evolutionary stage explanation for WLAGNs.

Abstract

Weak emission-line active galactic nuclei (WLAGNs) are radio-quiet active galactic nuclei (AGNs) that have nearly featureless optical spectra. We investigate the ultraviolet to mid-infrared spectral energy distributions of 73 WLAGNs (0.4<z<3) and find that most of them are similar to normal AGNs. We also calculate the covering factor of warm dust of these 73 WLAGNs. No significant difference is indicated by a KS test between the covering factor of WLAGNs and normal AGNs in the common range of bolometric luminosity. The implication for several models of WLAGNs is discussed. The super-Eddington accretion is unlikely the dominant reason for the featureless spectrum of a WLAGN. The present results favor the evolution scenario, i.e., WLAGNs are in a special stage of AGNs.