The Ionized Gas and Nuclear Environment in NGC 3783. I. Time-averaged 900 Kilosecond Chandra Grating Spectroscopy

By S. Kaspi, W. N. Brandt, I. George, H. Netzer, D. Crenshaw, J. Gabel, F. Hamann, M. Kaiser, A. Koratkar, S. Kraemer and 8 more. 2002

230 citations recorded by the source corpus.

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 Kα line, which indicates that it arises in cold, Compton-thick gas.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics, Radiation

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Citations in the corpus

A high-velocity ionized outflow and XUV photosphere in the narrow emission line quasar PG1211+143 (2003, background): “…developments in X-ray studies of AGN has been the observation, from high resolution grating spectra obtained with Chandra and XMM-Newton, of complex absorption indicating circumnuclear (often outflowing) matter existing in a wide range of ionisation states (eg Sako et al. 2001, Kaspi et al. 2002).”
Fueling Low-Level AGN Activity through Stochastic Accretion of Cold Gas (2006, background): “The “warm absorber” seen in soft X-rays is also indicative of a significant outflow generated local to the AGN (e.g., Laor et al. 1997, and references therein), accelerating radially to larger terminal velocities& a few 100kms−1 (Ruiz et al. 2001; Kaspi et al. 2002).”
CHANDRA Detects Relativistic Broad Absorption Lines from APM 08279+5255 (2002, background): “Recently, narrow absorption lines (NALs) in the X-ray band have been detected in Chandra andXMM-Newton observations of bright Seyfert 1 galaxies (e.g., Kaspi et al. 2002).”
THE SPIN OF THE SUPERMASSIVE BLACK HOLE IN NGC 3783 (2011, methodology): “…a high-column density and multi-component warm absorber (WA) that has been studied well by every spectroscopic X-ray observatory, including a 900 ks campaign by Chandra using the High-Energy Transmission Grating Spectrometer (HETGS; Kaspi et al. 2002; Krongold et al. 2003; Netzer et al. 2003).”
Fluorescent iron lines as a probe of astrophysical black hole systems (2002, background): “ clearly display the resonant absorption lines of oxygen that are expected to accompany the photoelectric edges (e.g., see the fabulous X-ray spectrum of NGC 3783 obtained by Kaspi and collaborators; [223]). However, in MCG–6-30-15, an XMM-Newton grating spectrum showed that the simple warm absorber”
THE CORES OF THE Fe Kα LINES IN ACTIVE GALACTIC NUCLEI: AN EXTENDED CHANDRA HIGH ENERGY GRATING SAMPLE (2010, methodology): “Detailed results from the six Chandra HETGS observations of this source have been presented by Yaqoob et al. (2005) and Kaspi et al. (2001, 2002), and our re-analysis is consistent with the previous results.”
The X-Ray Spectral Properties of SCUBA Galaxies (2005, unknown): “Chartas et al. 2002; Kaspi et al. 2002; Ogle et al. 2003).”
Simultaneous Chandra and RXTE Spectroscopy of the Microquasar H1743–322: Clues to Disk Wind and Jet Formation from a Variable Ionized Outflow (2004, background): “In both source classes, the velocity of the X-ray wind is on the order of few ; 100 km s 1 (see, e.g., Kaspi et al. 2002), suggesting that the winds may originate at similar distances from the central black hole.”
Toward a Self-Consistent Model of the Ionized Absorber in NGC 3783 (2003, methodology): “Component outflowing at 1345 km s−1 In the 900 ksec spectrum Kaspi et al. (2002) found evidence for two X-ray ab- sorbers in the lines of O vii, but could not conclude the same in those of Ne x.”
An X-ray spectral model for Compton-thick toroidal reprocessors (2009, background): “Evidence for the Compton shoulder has already been found in some sources (e.g. see Iwasawa, Fabian, & Matt 1997; Matt 2002; Kaspi et al. 2002; Watanabe et al. 2003; Yaqoob et al. 2005), although detections of the Compton shoulder to date have been ambiguous.”
The Ionized Gas and Nuclear Environment in NGC 3783. IV. Variability and Modeling of the 900 Kilosecond Chandra Spectrum (2003, background): “The object has been observed extensively with almost all X-ray instruments, most recently byChandra (Kaspi et al. 2002, hereafter Paper I) and XMM-Newton (Blustin et al. 2002).”
A long hard look at MCG–6-30-15 with XMM-Newton (2002, background): “Examples of strong, narrow lines have been foundin NGC 3783 (Kaspi et al. 2002; Reeves et al. 2003), NGC 5548 (Yaqoob et al. 2001; Pounds et al. 2003a), NGC 4151 (Schurch et al. 2003), and NGC 3227 (Reeves 2003).”
The nature and origin of Seyfert warm absorbers (2004, background): “…about different sources: at least some of the components of the X-ray and UV absorbers have been claimed to have a common origin in NGC 3783 (Kaspi et al. 2002; Gabel et al. 2003), NGC 3516 (Kraemer et al. 2002), NGC 7469 (Kriss et al. 2003; Blustin et al. 2003) and Ark 564 (Romano et al.…”
Relativistic X-Ray Lines from the Inner Accretion Disks Around Black Holes (2007, methodology): “In an analysis of a 900 ksec Chandra/HETGS spectrum, Kaspi et al. (2002) report the detection of a Compton edge in the narrow component of the Fe K line, but do not consider a global spectral model appropriate for broad line studies.”