Physical Conditions in the X-ray Emission-line Gas in NGC 1068

Abstract

We present a detailed, photoionization modeling analysis of XMM-Newton/Reflection Grating Spectrometer observations of the Seyfert 2 galaxy NGC 1068. The spectrum, previously analyzed by Kinkhabwala et al. (2002), reveals a myriad of soft-Xray emission lines, including those from H- and He-like carbon, nitrogen, oxygen, and neon, and M- and L-shell iron. As noted in the earlier analysis, based on the narrowness of the radiative recombination continua, the electron temperatures in the emission-line gas are consistent with photoionization, rather than collisional ionization. The strengths of the carbon and nitrogen emission lines, relative to those of oxygen, suggest unusual elemental abundances, which we attribute to star-formation history of the host galaxy. Overall, the emission-lines are blue-shifted with respect to systemic, with radial velocities ~ 160 km/s, similar to that of [O III] 5007, and thus consistent with the kinematics and orientation of the optical emission-line gas and, hence, likely part of an AGN-driven outflow. We were able to achieve an acceptable fit to most of the strong emission-lines with a two-component photoionization model, generated with Cloudy. The two components have ionization parameters and column densities of logU = -0.05 and 1.22, and logN(H) = 20.85 and 21.2, and covering factors of 0.35 and 0.84, respectively. The total mass of the X-ray gas is roughly of an order of magnitude greater than the mass of ionized gas determined from optical and near-IR spectroscopy, which indicates that it may be the dominant component of the narrow line region. Furthermore, we suggest that the medium which produces the scattered/polarized optical emission in NGC~1068 possesses similar physical characteristics to those of the more highly-ionized of the X-ray model components.

32 pages, 7 Figures. Accepted for publication in the Astrophysical Journal

References in corpus (7)

• Kinematics of the Narrow-Line Region in the Seyfert 2 Galaxy NGC 1068: Dynamical Effects of the Radio Jet
• New Indicators for AGN Power: The Correlation Between [O IV] lambda 25.89 micron and Hard X-ray Luminosity for Nearby Seyfert Galaxies
• Dynamics of the Narrow-Line Region in the Seyfert 2 Galaxy NGC 1068
• Feeding Versus Feedback in NGC1068 probed with Gemini NIFS. I. Excitation
• Large-Scale Parker Winds in Active Galactic Nuclei
• A Photoionization Model For The Soft X-Ray Spectrum Of NGC 4151
• A Cloudy/Xspec Interface

Cited by in corpus (12)

• Quantifying Feedback from Narrow Line Region Outflows in Nearby Active Galaxies. III. Results for the Seyfert 2 Galaxies Markarian 3, Markarian 78, and NGC 1068
• Physical Conditions in Ultra Fast Outflows in AGN
• A molecular line survey toward the nearby galaxies NGC 1068, NGC 253, and IC 342 at 3 mm with the Nobeyama 45 m radio telescope: The data
• Variability of the coronal line region in NGC 4151
• Mass Outflow of the X-ray Emission Line Gas in NGC 4151
• Deep Chandra Observations of NGC 5728: Morphology and Spectral Properties of the Extended X-ray Emission
• Photoionisation Modelling of the X-ray Emission Line Regions within the Seyfert 2 AGN NGC 1068
• Line absorption of He-like triplet lines by Li-like ions. Caveats of using line ratios of triplets for plasma diagnostics
• Hubble Space Telescope [O III] Emission-Line Kinematics in Two Nearby QSO2s: A Case for X-ray Feedback
• Direct observation of the Broad Line Region in X-rays during the low state of NGC4051
• Probing AGN-ISM Feedback through Extended X-ray Emission in ESO 137-G034
• AGN-host interaction in IC 5063. I. Large-scale X-ray morphology and spectral analysis