A CENSUS OF X-RAY GAS IN NGC 1068: RESULTS FROM 450 ks of CHANDRA HIGH ENERGY TRANSMISSION GRATING OBSERVATIONS
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Kallman-2014-A census of X-ray ga.pdf
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Author(s)
Kallman, T. R.
Evans, Daniel A.
Longinotti, Anna Lia
Marshall, Herman Lee
Canizares, Claude R.
Nowak, Michael A.
Schulz, Norbert S.
Date Issued
December 2013
Journal
The Astrophysical Journal
Publisher
IOP Publishing
Citation
Kallman, T., Daniel A. Evans, H. Marshall, C. Canizares, A. Longinotti, M. Nowak, and N. Schulz. “A CENSUS OF X-RAY GAS IN NGC 1068: RESULTS FROM 450 Ks of CHANDRA HIGH ENERGY TRANSMISSION GRATING OBSERVATIONS.” The Astrophysical Journal 780, no. 2 (December 17, 2013): 121. © 2014 The American Astronomical Society
Version
Final published version
Abstract
We present models for the X-ray spectrum of the Seyfert 2 galaxy NGC 1068. These are fitted to data obtained using the High Energy Transmission Grating on Chandra. The data show line and radiative recombination continuum emission from a broad range of ions and elements. The models explore the importance of excitation processes for these lines including photoionization followed by recombination, radiative excitation by absorption of continuum radiation, and inner shell fluorescence. The models show that the relative importance of these processes depends on the conditions in the emitting gas and that no single emitting component can fit the entire spectrum. In particular, the relative importance of radiative excitation and photoionization/recombination differs according to the element and ion stage emitting the line. This in turn implies a diversity of values for the ionization parameter of the various components of gas responsible for the emission, ranging from log(ξ) = 1 to 3. Using this, we obtain an estimate for the total amount of gas responsible for the observed emission. The mass flux through the region included in the HETG extraction region is approximately 0.3 M [subscript ☉] yr[superscript –1], assuming ordered flow at the speed characterizing the line widths. This can be compared with what is known about this object from other techniques.
MIT Department
MIT Kavli Institute for Astrophysics and Space Research
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DOI of Published Version
https://doi.org/10.1088/0004-637X/780/2/121
