A Census of X-ray Gas in NGC 1068: Results From 450 ks of CHANDRA High Energy Transmisson Grating Observations

[摘要] We present models for the X-ray spectrum of the Seyfert 2 galaxy NGC 1068. These are fitted to data obtained usingthe High Energy Transmission Grating on Chandra. The data show line and radiative recombination continuumemission from a broad range of ions and elements. The models explore the importance of excitation processes forthese lines including photoionization followed by recombination, radiative excitation by absorption of continuumradiation, and inner shell fluorescence. The models show that the relative importance of these processes depends onthe 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 elementand ion stage emitting the line. This in turn implies a diversity of values for the ionization parameter of the variouscomponents of gas responsible for the emission, ranging from log(E ) = 1 to 3. Using this, we obtain an estimatefor the total amount of gas responsible for the observed emission. The mass flux through the region included in theHETG extraction region is approximately 0.3M/yr, assuming ordered flow at the speed characterizing the linewidths. This can be compared with what is known about this object from other techniques.

[发布日期] 2013-12-17

[学科分类] 天体物理学