The ionized gas and nuclear environment in NGC 3783. I. Time-averaged 900 kilosecond Chandra grating spectroscopy

Shai Kaspi, W. N. Brandt, Ian M. George, Hagai Netzer, D. Michael Crenshaw, Jack Gabel, Frederick W. Hamann, Mary Elizabeth Kaiser, Anuradha Koratkar, Steven B. Kraemer, Gerard A. Kriss, Smita Mathur, Richard F. Mushotzky, Kirpal Nandra, Bradley M. Peterson, Joseph C. Shields, T. J. Turner, Wei Zheng

Research output: Contribution to journalArticle

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Abstract

We present results from a 900 ks exposure of NGC 3783 with the High-Energy Transmission Grating Spectrometer on board the Chandra X-Ray Observatory. The resulting X-ray spectrum, which covers the 0.5-10 keV energy range, has the best combination of signal-to-noise ratio and resolution ever obtained for an AGN. This spectrum reveals absorption lines from H-like and He-like ions of N, O, Ne, Mg, Al, Si, and S. There are also possible absorption lines from H-like and He-like Ar and Ca as well as H-like C. We also identify inner-shell absorption from lower ionization ions such as Si VII-Si XII and S XII-S XIV. The iron absorption spectrum is very rich; L-shell lines of Fe XVII-Fe XXIV are detected, as well as probable resonance lines from Fe XXV. A strong complex of M-shell lines from iron ions is also detected in the spectrum. The absorption lines are blueshifted relative to the systemic velocity by a mean velocity of -590 ± 150 km s-1. We resolve many of the absorption lines, and their mean FWHM is 820 ± 280 km s-1. We do not find correlations between the velocity shifts or the FWHMs with the ionization potentials of the ions. Most absorption lines show asymmetry, having more extended blue wings than red wings. In O VII we have resolved this asymmetry to be from an additional absorption system at approximately -1300 km s -1. The two X-ray absorption systems are consistent in velocity shift and FWHM with the ones identified in the UV lines of C IV, N V, and H I. Equivalent width measurements for all absorption and emission lines are given and column densities are calculated for several ions. We resolve the narrow Fe Kα line at 6398.2 ± 3.3 eV to have an FWHM of 1720 ± 360 km s-1, which suggests that this narrow line may be emitted from the outer part of the broad-line region or the inner part of the torus. We also detect a "Compton shoulder" redward of the narrow Fe Ka line, which indicates that it arises in cold, Compton-thick gas.

Original languageEnglish
Pages (from-to)643-662
Number of pages20
JournalAstrophysical Journal
Volume574
Issue number2 I
DOIs
StatePublished - Aug 1 2002
Externally publishedYes

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ionized gases
spectroscopy
gratings
gas
ion
absorption spectrum
shell
ions
wings
asymmetry
ionization
absorption spectra
iron
K lines
x rays
shift
shoulders
resonance lines
ionization potentials
signal-to-noise ratio

All Science Journal Classification (ASJC) codes

  • Space and Planetary Science
  • Nuclear and High Energy Physics

Cite this

The ionized gas and nuclear environment in NGC 3783. I. Time-averaged 900 kilosecond Chandra grating spectroscopy. / Kaspi, Shai; Brandt, W. N.; George, Ian M.; Netzer, Hagai; Crenshaw, D. Michael; Gabel, Jack; Hamann, Frederick W.; Kaiser, Mary Elizabeth; Koratkar, Anuradha; Kraemer, Steven B.; Kriss, Gerard A.; Mathur, Smita; Mushotzky, Richard F.; Nandra, Kirpal; Peterson, Bradley M.; Shields, Joseph C.; Turner, T. J.; Zheng, Wei.

In: Astrophysical Journal, Vol. 574, No. 2 I, 01.08.2002, p. 643-662.

Research output: Contribution to journalArticle

Kaspi, S, Brandt, WN, George, IM, Netzer, H, Crenshaw, DM, Gabel, J, Hamann, FW, Kaiser, ME, Koratkar, A, Kraemer, SB, Kriss, GA, Mathur, S, Mushotzky, RF, Nandra, K, Peterson, BM, Shields, JC, Turner, TJ & Zheng, W 2002, 'The ionized gas and nuclear environment in NGC 3783. I. Time-averaged 900 kilosecond Chandra grating spectroscopy', Astrophysical Journal, vol. 574, no. 2 I, pp. 643-662. https://doi.org/10.1086/341113
Kaspi, Shai ; Brandt, W. N. ; George, Ian M. ; Netzer, Hagai ; Crenshaw, D. Michael ; Gabel, Jack ; Hamann, Frederick W. ; Kaiser, Mary Elizabeth ; Koratkar, Anuradha ; Kraemer, Steven B. ; Kriss, Gerard A. ; Mathur, Smita ; Mushotzky, Richard F. ; Nandra, Kirpal ; Peterson, Bradley M. ; Shields, Joseph C. ; Turner, T. J. ; Zheng, Wei. / The ionized gas and nuclear environment in NGC 3783. I. Time-averaged 900 kilosecond Chandra grating spectroscopy. In: Astrophysical Journal. 2002 ; Vol. 574, No. 2 I. pp. 643-662.
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T1 - The ionized gas and nuclear environment in NGC 3783. I. Time-averaged 900 kilosecond Chandra grating spectroscopy

AU - Kaspi, Shai

AU - Brandt, W. N.

AU - George, Ian M.

AU - Netzer, Hagai

AU - Crenshaw, D. Michael

AU - Gabel, Jack

AU - Hamann, Frederick W.

AU - Kaiser, Mary Elizabeth

AU - Koratkar, Anuradha

AU - Kraemer, Steven B.

AU - Kriss, Gerard A.

AU - Mathur, Smita

AU - Mushotzky, Richard F.

AU - Nandra, Kirpal

AU - Peterson, Bradley M.

AU - Shields, Joseph C.

AU - Turner, T. J.

AU - Zheng, Wei

PY - 2002/8/1

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N2 - We present results from a 900 ks exposure of NGC 3783 with the High-Energy Transmission Grating Spectrometer on board the Chandra X-Ray Observatory. The resulting X-ray spectrum, which covers the 0.5-10 keV energy range, has the best combination of signal-to-noise ratio and resolution ever obtained for an AGN. This spectrum reveals absorption lines from H-like and He-like ions of N, O, Ne, Mg, Al, Si, and S. There are also possible absorption lines from H-like and He-like Ar and Ca as well as H-like C. We also identify inner-shell absorption from lower ionization ions such as Si VII-Si XII and S XII-S XIV. The iron absorption spectrum is very rich; L-shell lines of Fe XVII-Fe XXIV are detected, as well as probable resonance lines from Fe XXV. A strong complex of M-shell lines from iron ions is also detected in the spectrum. The absorption lines are blueshifted relative to the systemic velocity by a mean velocity of -590 ± 150 km s-1. We resolve many of the absorption lines, and their mean FWHM is 820 ± 280 km s-1. We do not find correlations between the velocity shifts or the FWHMs with the ionization potentials of the ions. Most absorption lines show asymmetry, having more extended blue wings than red wings. In O VII we have resolved this asymmetry to be from an additional absorption system at approximately -1300 km s -1. The two X-ray absorption systems are consistent in velocity shift and FWHM with the ones identified in the UV lines of C IV, N V, and H I. Equivalent width measurements for all absorption and emission lines are given and column densities are calculated for several ions. We resolve the narrow Fe Kα line at 6398.2 ± 3.3 eV to have an FWHM of 1720 ± 360 km s-1, which suggests that this narrow line may be emitted from the outer part of the broad-line region or the inner part of the torus. We also detect a "Compton shoulder" redward of the narrow Fe Ka line, which indicates that it arises in cold, Compton-thick gas.

AB - We present results from a 900 ks exposure of NGC 3783 with the High-Energy Transmission Grating Spectrometer on board the Chandra X-Ray Observatory. The resulting X-ray spectrum, which covers the 0.5-10 keV energy range, has the best combination of signal-to-noise ratio and resolution ever obtained for an AGN. This spectrum reveals absorption lines from H-like and He-like ions of N, O, Ne, Mg, Al, Si, and S. There are also possible absorption lines from H-like and He-like Ar and Ca as well as H-like C. We also identify inner-shell absorption from lower ionization ions such as Si VII-Si XII and S XII-S XIV. The iron absorption spectrum is very rich; L-shell lines of Fe XVII-Fe XXIV are detected, as well as probable resonance lines from Fe XXV. A strong complex of M-shell lines from iron ions is also detected in the spectrum. The absorption lines are blueshifted relative to the systemic velocity by a mean velocity of -590 ± 150 km s-1. We resolve many of the absorption lines, and their mean FWHM is 820 ± 280 km s-1. We do not find correlations between the velocity shifts or the FWHMs with the ionization potentials of the ions. Most absorption lines show asymmetry, having more extended blue wings than red wings. In O VII we have resolved this asymmetry to be from an additional absorption system at approximately -1300 km s -1. The two X-ray absorption systems are consistent in velocity shift and FWHM with the ones identified in the UV lines of C IV, N V, and H I. Equivalent width measurements for all absorption and emission lines are given and column densities are calculated for several ions. We resolve the narrow Fe Kα line at 6398.2 ± 3.3 eV to have an FWHM of 1720 ± 360 km s-1, which suggests that this narrow line may be emitted from the outer part of the broad-line region or the inner part of the torus. We also detect a "Compton shoulder" redward of the narrow Fe Ka line, which indicates that it arises in cold, Compton-thick gas.

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