Photoionisation Modelling of the X-ray Emission Line Regions within the Seyfert 2 AGN NGC 1068

Abstract

We investigate the photoionised X-ray emission line regions (ELRs) within the Seyfert 2 galaxy NGC 1068, to determine if there are any characteristic changes between observations taken fourteen years apart. We compare XMM-Newton observations collected in 2000 and 2014, simultaneously fitting the reflection grating spectrometer (RGS) and EPIC-pn spectra of each epoch, for the first time, with the photoionisation model, PION, in SPEX. We find that four PION components are required to fit the majority of the emission lines in the spectra of NGC 1068, with $\log \xi =1-4$, $\log N_H>26m^{-2}$, and $v_{out}=-100$ to $-600km{s}^{-1}$ for both epochs. Comparing the ionisation state of the components shows almost no difference between the two epochs, while there is an increase in the total column density. To estimate the locations of these plasma regions from the central black hole we compare distance methods, excluding the variability arguments as there is no spectral change between observations. Although the methods are unable to constrain the distances, the locations are consistent with the narrow line region, with the possibility of the higher ionised component being part of the broad line region, but we cannot conclude this for certain. In addition, we find evidence for emission from collisionally ionised plasma, while previous analysis had suggested that collisional plasma emission was unlikely. However, although PION is unable to account for the FeXVII emission lines at 15 and 17 Å, we do not rule out that photoexcitation is a valid processes to produce these lines too. NGC 1068 has not changed, both in terms of the observed spectra or from our modelling, within the 14 year time period between observations. This suggests that the ELRs are fairly static relative to the 14 year time frame between observations, or there is no dramatic change in the black hole variability.

19 pages, 10 figures

References in corpus (17)

• Molecular line emission in NGC1068 imaged with ALMA. I An AGN-driven outflow in the dense molecular gas
• On the X-ray, optical emission line and black hole mass properties of local Seyfert galaxies
• A fast and long-lived outflow from the supermassive black hole in NGC 5548
• On the use of C-stat in testing models for X-ray spectra
• Molecular line emission in NGC1068 imaged with ALMA: II. The chemistry of the dense molecular gas
• Systematic comparison of photoionised plasma codes with application to spectroscopic studies of AGN in X-rays
• Chasing obscuration in type-I AGN: discovery of an eclipsing clumpy wind at the outer broad-line region of NGC 3783
• The mass-energy budget of the ionised outflow in NGC 7469
• ALMA imaging of C2H emission in the disk of NGC1068
• X-ray spectra of the Fe-L complex
• Linking the X-ray and infrared properties of star-forming galaxies at z<1.5
• X-ray reflection in the nearby Seyfert 2 galaxy NGC 1068
• Evidence for Radiation Pressure Compression in the X-ray Narrow Line Region of Seyfert galaxies
• Physical Conditions in the X-ray Emission-line Gas in NGC 1068
• Direct observation of the Broad Line Region in X-rays during the low state of NGC4051
• Chandra imaging of the $\sim$kpc extended outflow in 1H 0419-577
• Canonical X-Ray Fluorescence Line Intensities as Column Density Indicators

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• A Study of the Soft X-ray Emission Lines in NGC 4151 I. Kinematic Properties of the Plasma Wind
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