PHL 1811 Analogs: A Population of X-ray Weak Quasars

TL;DR

This paper identifies a population of X-ray weak quasars with unique UV emission-line features, suggesting they have wind-dominated broad emission-line regions and proposing a unifying AGN geometry model.

Contribution

It introduces PHL 1811 analogs as a distinct class of X-ray weak quasars with specific emission-line properties and proposes a unifying model for weak-line quasars.

Findings

PHL 1811 analogs are about 13 times weaker in X-ray emission.

Strong correlation between X-ray weakness and UV emission-line properties.

Proposed AGN geometry unifies PHL 1811 analogs with weak-line quasars.

Abstract

We report on a population of X-ray weak quasars with similar UV emission-line properties to those of the remarkable quasar PHL 1811. All radio-quiet PHL 1811 analogs are notably X-ray weak by a mean factor of ~13, with hints of heavy X-ray absorption. Correlations between the X-ray weakness and UV emission-line properties suggest that PHL 1811 analogs may have extreme wind-dominated broad emission-line regions (BELRs). We propose an AGN geometry that can potentially unify the PHL 1811 analogs and the general population of weak-line quasars.