On the peculiar properties of the narrow-line quasar PG 1543+489

TL;DR

This study analyzes four XMM-Newton observations of the narrow-line quasar PG 1543+489, revealing a relativistic iron line and steep spectrum consistent with an ionized reflection near the black hole, with light-bending effects explaining the large iron line EW.

Contribution

It provides evidence supporting the ionized reflection model with light-bending effects as the explanation for the quasar's X-ray spectral features, while also considering alternative absorption models.

Findings

Detection of a broad, relativistic iron K_alpha emission line.

Large equivalent width of the iron line (~3.1 keV) explained by light-bending effects.

Spectral properties remain stable over three years, favoring the reflection model.

Abstract

We present the analysis of four XMM-Newton observations of the narrow-line quasar PG 1543+489 at z=0.400 carried out over a rest-frame time-scale of about three years. The X-ray spectrum is characterized by a broad, relativistic iron K_alpha emission line and a steep photon index, which can be both explained by a ionized reflection model, where the source of X-ray photons is presumably very close to the black hole. If this were the case, strong light-bending effects are expected, and actually they provide the most plausible explanation for the large equivalent width (EW=3.1+/-0.8 keV in the source rest frame) of the iron line. Although the light-bending model provides a good description of the X-ray data of PG 1543+489, it is not possible to rule out an absorption model, where obscuring matter partially covers the X-ray source. However, the apparent lack of variations in the properties of the absorber over the time-scale probed by our observations may indicate that this model is less likely.