XMM-Newton unveils the complex iron K alpha region of Mrk 279

TL;DR

This study uses XMM-Newton data to analyze the complex iron K alpha emission in Mrk 279, revealing contributions from the accretion disk, broad line region, and torus, with detailed modeling of ionized gas components.

Contribution

First quantification of the broad line region's contribution to the Fe K alpha luminosity in Mrk 279 using the 'locally optimally emitting cloud' model.

Findings

The broad Fe K alpha line can be modeled as a single broad component or two components.

The BLR contributes only about 3% to the broad Fe K alpha luminosity.

The highly ionized gas producing FeXXVI is likely from a high-density, highly ionized outer torus layer.

Abstract

We present the results of a ~160 ks-long XMM-Newton observation of the Seyfert 1 galaxy Mrk 279. The spectrum shows evidence of both broad and narrow emission features. The Fe K alpha line may be equally well explained by a single broad Gaussian (FWHM~10,000 km/s) or by two components: an unresolved core plus a very broad profile (FWHM~14,000 km/s). For the first time we quantified, via the "locally optimally emitting cloud" model, the contribution of the broad line region (BLR) to the absolute luminosity of the broad component of the Fe K alpha at 6.4 keV. We find that the contribution of the BLR is only ~3%. In the two-line component scenario, we also evaluated the contribution of the highly ionized gas component, which produces the FeXXVI line in the iron K region. This contribution to the narrow core of the Fe K alpha line is marginal <0.1%. Most of the luminosity of the unresolved, component of Fe K alpha may come from the obscuring torus, while the very-broad associated component may come from the accretion disk. However, models of reflection by cold gas are difficult to test because of the limited energy band. The FeXXVI line at 6.9 keV is consistent to be produced in a high column density (N_H~10^23 cm^{-2}), extremely ionized (log\xi~5.5-7) gas. This gas may be a highly ionized outer layer of the torus.