High-Resolution X-Ray Spectroscopy and Modeling of the Absorbing and Emitting Outflow in NGC 3783

By S. Kaspi, W. N. Brandt, H. Netzer, I. George, G. Chartas, E. Behar, R. Sambruna, G. Garmire, J. Nousek. 2001

145 citations recorded by the source corpus.

The high-resolution X-ray spectrum of NGC 3783 shows several dozen absorption lines and a few emission lines from the H-like and He-like ions of O, Ne, Mg, Si, and S, as well as from Fe XVII-Fe XXIII L-shell transitions. We have reanalyzed the Chandra HETGS spectrum using better flux and wavelength calibrations, along with more robust methods. Combining several lines from each element, we clearly demonstrate the existence of the absorption lines and determine that they are blueshifted relative to the systemic velocity by -610 ± 130 km s-1. We find the Ne absorption lines in the High-Energy Grating spectrum to be resolved with FWHM = 840 km s-1; no other lines are resolved. The emission lines are consistent with being at the systemic velocity. We have used regions in the spectrum where no lines are expected to determine the X-ray continuum, and we model the absorption and emission lines using photoionized-plasma calculations. The model consists of two absorption components, with different covering factors, which have an order-of-magnitude difference in their ionization parameters. The two components are spherically outflowing from the active galactic nucleus, and thus contribute to both the absorption and the emission via P Cygni profiles. The model also clearly requires O VII and O VIII absorption edges. The low-ionization component of our model can plausibly produce UV absorption lines with equivalent widths consistent with those observed from NGC 3783. However, we note that this result is highly sensitive to the unobservable UV to X-ray continuum, and the available UV and X-ray observations cannot firmly establish the relationship between the UV and X-ray absorbers. We find good agreement between the Chandra spectrum and simultaneous ASCA and RXTE observations. The 1 keV deficit previously found when modeling ASCA data probably arises from iron L-shell absorption lines not included in previous models. We also set an upper limit on the FWHM of the narrow Fe Kα emission line of 3250 km s-1. This is consistent with this line originating outside the broad-line region, possibly from a torus.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/6104bd5706174a7b8198c0bafb5607c8b58c373d

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Citations in the corpus

An Overview of the Performance and Scientific Results from the Chandra X‐Ray Observatory (2001, methodology): “For NGC 3783, detailed modeling of an absorber with two ionization components does a remarkably good job of reproducing the observed line strengths (Kaspi et al. 2001).”
THE CORES OF THE Fe Kα LINES IN ACTIVE GALACTIC NUCLEI: AN EXTENDED CHANDRA HIGH ENERGY GRATING SAMPLE (2010, result): “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 Ionized Gas and Nuclear Environment in NGC 3783. I. Time-averaged 900 Kilosecond Chandra Grating Spectroscopy (2002, unknown): “To examine further th absorption we created “velocity spectra” by adding, in velocity space, several absorption lines from the same ion (see also Kaspi et al. 2001).”
Warm Absorbers in Active Galactic Nuclei: A Multitemperature Wind (2001, methodology): “No alteration in the Kaiser et al. (2001, in preparation) spectrum was necessary to accomplish this, but to achieve this with the Kaspi et al. (2001) spectrum we added a new component at 0.1 eV.”
The Ionized Gas and Nuclear Environment in NGC 3783. IV. Variability and Modeling of the 900 Kilosecond Chandra Spectrum (2003, background): “Kaspi et al. (2001) see no evidence for this feature in the 2000 Chandra observation.”
Toward a Self-Consistent Model of the Ionized Absorber in NGC 3783 (2003, methodology): “(2) As already stressed by Mathur et al. (1994, see also Kaspi et al. 2001), the actual ionization parameters are strongly dependent on the far UV shape of the SED.”
Compton reflection and iron fluorescence in BeppoSAX observations of Seyfert type 1 galaxies (2002, methodology): “We note on the other hand the good agreement in our values of Γ and Nw with those obtained by Kaspi et al. (2001) in fitting the “line free zones” of the HETGS spectral data with a power law and a warm absorber.”
Simultaneous X-ray/optical/UV snapshots of active galactic nuclei from XMM–Newton: spectral energy distributions for the reverberation mapped sample (2008, methodology): “This object is known to have an outflowing warm absorber (Kaspi et al. 2001), as discussed in detail by Reeves et al. (2004), and we obtain a value of log(NH/cm−2)∼ 21.3–21.4 from our simple ZWABS model fit.”