skip to main content

SciTech ConnectSciTech Connect

Title: A Census of X-ray gas in NGC 1068: Results from 450 ks of Chandra high energy transmission grating observations

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 {sub ☉} yr{sup –1}, assuming ordered flow at the speed characterizing the line widths. This canmore » be compared with what is known about this object from other techniques.« less
Authors:
 [1] ;  [2] ; ; ; ;  [3] ;  [4]
  1. NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 12138 (United States)
  3. Kavli Institute for Astrophysics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
  4. European Space Astronomy Centre, ESA, P.O. Box 78, E-28691 Villanueva de la Cañada, Madrid (Spain)
Publication Date:
OSTI Identifier:
22348258
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 780; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; APPROXIMATIONS; COMPARATIVE EVALUATIONS; EXCITATION; EXTRACTION; FLUORESCENCE; LINE WIDTHS; MASS; PHOTOIONIZATION; POWER TRANSMISSION; RECOMBINATION; VELOCITY; X RADIATION; X-RAY GALAXIES; X-RAY SPECTRA