Density diagnostics of ionized outflows in active galactic nuclei

X-ray and UV absorption lines from metastable levels in Be-like to C-like ions

Junjie Mao, J. S. Kaastra, M. Mehdipour, A. J. J. Raassen, Liyi Gu, J. M. Miller

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Ionized outflows in Active Galactic Nuclei (AGN) are thought to influence their nuclear and local galactic environment. However, the distance of the outflows with respect to the central engine is poorly constrained, which limits our understanding of their kinetic power as a cosmic feedback channel. Therefore, the impact of AGN outflows on their host galaxies is uncertain. However, when the density of the outflows is known, their distance can be immediately obtained from their modelled ionization parameter. With the new self-consistent PhotoIONization (PION) model in the SPEX code, we are able to calculate detailed level populations, including the ground and metastable levels. This enables us to determine under what physical conditions the metastable levels are significantly populated. We then identify characteristic lines from these metastable levels in the 1 -- 2000 {\AA} wavelength range. In the large density range of $n_H \in (10^6, 10^{20} m^{-3}$, the metastable levels 2s 2p $(^3P_{0-2})$ in Be-like ions can be significantly populated. For B-like ions, merely the first excited level 2s$^2$ 2p $(^2P_{3/2})$ can be used as a density probe. For C-like ions, the first two excited levels 2s$^2$ 2p$^2$ ($^3P_1$ and $^3P_2$) are better density probes than the next two excited levels 2s$^2$ 2p$^2$ ($^1S_0$ and $^1D_2$). Different ions in the same isoelectronic sequence cover not only a wide range of ionization parameter, but also a wide range of density. On the other hand, within the same isonuclear sequence, less ionized ions probe lower density and smaller ionization parameter. Finally, we re-analyzed the high-resolution grating spectra of NGC 5548 observed with Chandra in January 2002, using a set of PION components to account for the ionized outflow. We derive lower (or upper) limits of plasma density in five out of six PION components, based on the presence (or absence) of the metastable absorption lines.
Original language English A100 14 Astronomy and Astrophysics 607 21 Nov 2017 https://doi.org/10.1051/0004-6361/201731378 E-pub ahead of print - 21 Nov 2017

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active galactic nuclei
outflow
ion
ions
x rays
ionization
photoionization
probe
ion probes
isoelectronic sequence
probes
gratings (spectra)
engine
plasma density
engines
wavelength
plasma
kinetics
galaxies
high resolution

Keywords

• astro-ph.HE
• plasma
• atomic data
• atomic processes
• techniques: spectroscopic
• X-rays: galaxies
• galaxies: active
• NGC5548

Cite this

@article{6c5d5c8ce8d749afa75c2f463e1f64a9,
title = "Density diagnostics of ionized outflows in active galactic nuclei: X-ray and UV absorption lines from metastable levels in Be-like to C-like ions",
abstract = "Ionized outflows in Active Galactic Nuclei (AGN) are thought to influence their nuclear and local galactic environment. However, the distance of the outflows with respect to the central engine is poorly constrained, which limits our understanding of their kinetic power as a cosmic feedback channel. Therefore, the impact of AGN outflows on their host galaxies is uncertain. However, when the density of the outflows is known, their distance can be immediately obtained from their modelled ionization parameter. With the new self-consistent PhotoIONization (PION) model in the SPEX code, we are able to calculate detailed level populations, including the ground and metastable levels. This enables us to determine under what physical conditions the metastable levels are significantly populated. We then identify characteristic lines from these metastable levels in the 1 -- 2000 {\AA} wavelength range. In the large density range of $n_H \in (10^6, 10^{20} m^{-3}$, the metastable levels 2s 2p $(^3P_{0-2})$ in Be-like ions can be significantly populated. For B-like ions, merely the first excited level 2s$^2$ 2p $(^2P_{3/2})$ can be used as a density probe. For C-like ions, the first two excited levels 2s$^2$ 2p$^2$ ($^3P_1$ and $^3P_2$) are better density probes than the next two excited levels 2s$^2$ 2p$^2$ ($^1S_0$ and $^1D_2$). Different ions in the same isoelectronic sequence cover not only a wide range of ionization parameter, but also a wide range of density. On the other hand, within the same isonuclear sequence, less ionized ions probe lower density and smaller ionization parameter. Finally, we re-analyzed the high-resolution grating spectra of NGC 5548 observed with Chandra in January 2002, using a set of PION components to account for the ionized outflow. We derive lower (or upper) limits of plasma density in five out of six PION components, based on the presence (or absence) of the metastable absorption lines.",
keywords = "astro-ph.HE, plasma, atomic data, atomic processes, techniques: spectroscopic, X-rays: galaxies, galaxies: active, NGC5548",
author = "Junjie Mao and Kaastra, {J. S.} and M. Mehdipour and Raassen, {A. J. J.} and Liyi Gu and Miller, {J. M.}",
year = "2017",
month = "11",
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doi = "10.1051/0004-6361/201731378",
language = "English",
volume = "607",
journal = "Astronomy and Astrophysics",
issn = "0004-6361",
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Density diagnostics of ionized outflows in active galactic nuclei : X-ray and UV absorption lines from metastable levels in Be-like to C-like ions. / Mao, Junjie; Kaastra, J. S.; Mehdipour, M.; Raassen, A. J. J.; Gu, Liyi; Miller, J. M.

In: Astronomy and Astrophysics, Vol. 607, A100, 21.11.2017.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Density diagnostics of ionized outflows in active galactic nuclei

T2 - X-ray and UV absorption lines from metastable levels in Be-like to C-like ions

AU - Mao, Junjie

AU - Kaastra, J. S.

AU - Mehdipour, M.

AU - Raassen, A. J. J.

AU - Gu, Liyi

AU - Miller, J. M.

PY - 2017/11/21

Y1 - 2017/11/21

N2 - Ionized outflows in Active Galactic Nuclei (AGN) are thought to influence their nuclear and local galactic environment. However, the distance of the outflows with respect to the central engine is poorly constrained, which limits our understanding of their kinetic power as a cosmic feedback channel. Therefore, the impact of AGN outflows on their host galaxies is uncertain. However, when the density of the outflows is known, their distance can be immediately obtained from their modelled ionization parameter. With the new self-consistent PhotoIONization (PION) model in the SPEX code, we are able to calculate detailed level populations, including the ground and metastable levels. This enables us to determine under what physical conditions the metastable levels are significantly populated. We then identify characteristic lines from these metastable levels in the 1 -- 2000 {\AA} wavelength range. In the large density range of $n_H \in (10^6, 10^{20} m^{-3}$, the metastable levels 2s 2p $(^3P_{0-2})$ in Be-like ions can be significantly populated. For B-like ions, merely the first excited level 2s$^2$ 2p $(^2P_{3/2})$ can be used as a density probe. For C-like ions, the first two excited levels 2s$^2$ 2p$^2$ ($^3P_1$ and $^3P_2$) are better density probes than the next two excited levels 2s$^2$ 2p$^2$ ($^1S_0$ and $^1D_2$). Different ions in the same isoelectronic sequence cover not only a wide range of ionization parameter, but also a wide range of density. On the other hand, within the same isonuclear sequence, less ionized ions probe lower density and smaller ionization parameter. Finally, we re-analyzed the high-resolution grating spectra of NGC 5548 observed with Chandra in January 2002, using a set of PION components to account for the ionized outflow. We derive lower (or upper) limits of plasma density in five out of six PION components, based on the presence (or absence) of the metastable absorption lines.

AB - Ionized outflows in Active Galactic Nuclei (AGN) are thought to influence their nuclear and local galactic environment. However, the distance of the outflows with respect to the central engine is poorly constrained, which limits our understanding of their kinetic power as a cosmic feedback channel. Therefore, the impact of AGN outflows on their host galaxies is uncertain. However, when the density of the outflows is known, their distance can be immediately obtained from their modelled ionization parameter. With the new self-consistent PhotoIONization (PION) model in the SPEX code, we are able to calculate detailed level populations, including the ground and metastable levels. This enables us to determine under what physical conditions the metastable levels are significantly populated. We then identify characteristic lines from these metastable levels in the 1 -- 2000 {\AA} wavelength range. In the large density range of $n_H \in (10^6, 10^{20} m^{-3}$, the metastable levels 2s 2p $(^3P_{0-2})$ in Be-like ions can be significantly populated. For B-like ions, merely the first excited level 2s$^2$ 2p $(^2P_{3/2})$ can be used as a density probe. For C-like ions, the first two excited levels 2s$^2$ 2p$^2$ ($^3P_1$ and $^3P_2$) are better density probes than the next two excited levels 2s$^2$ 2p$^2$ ($^1S_0$ and $^1D_2$). Different ions in the same isoelectronic sequence cover not only a wide range of ionization parameter, but also a wide range of density. On the other hand, within the same isonuclear sequence, less ionized ions probe lower density and smaller ionization parameter. Finally, we re-analyzed the high-resolution grating spectra of NGC 5548 observed with Chandra in January 2002, using a set of PION components to account for the ionized outflow. We derive lower (or upper) limits of plasma density in five out of six PION components, based on the presence (or absence) of the metastable absorption lines.

KW - astro-ph.HE

KW - plasma

KW - atomic data

KW - atomic processes

KW - techniques: spectroscopic

KW - X-rays: galaxies

KW - galaxies: active

KW - NGC5548

UR - https://arxiv.org/abs/1707.09552v2

U2 - 10.1051/0004-6361/201731378

DO - 10.1051/0004-6361/201731378

M3 - Article

VL - 607

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

M1 - A100

ER -