X-Ray Spectroscopy in the Microcalorimeter Era 4: Optical Depth Effects on the Soft X-Rays Studied with CLOUDY
Abstract
In this paper, we discuss atomic processes modifying the soft X-ray spectra from optical depth effects like photoelectric absorption and electron scattering suppressing the soft X-ray lines. We also show the enhancement in soft X-ray line intensities in a photoionized environment via continuum pumping. We quantify the suppression/enhancement by introducing a "line modification factor (f mod)." If 0 ≤ f mod ≤ 1, the line is suppressed, which could be the case in both collisionally ionized and photoionized systems. If f mod ≥ 1, the line is enhanced, which occurs in photoionized systems. Hybrid astrophysical sources are also very common, where the environment is partly photoionized and partly collisionally ionized. Such a system is V1223 Sgr, an Intermediate Polar binary. We show the application of our theory by fitting the first-order Chandra Medium Energy Grating (MEG) spectrum of V1223 Sgr with a combination of CLOUDY-simulated additive cooling-flow and photoionized models. In particular, we account for the excess flux for O VII, O VIII, Ne IX, Ne X, and Mg XI lines in the spectrum found in a recent study, which could not be explained with an absorbed cooling-flow model.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2022
- DOI:
- 10.3847/1538-4357/ac7eb9
- arXiv:
- arXiv:2207.02267
- Bibcode:
- 2022ApJ...935...70C
- Keywords:
-
- X-ray binary stars;
- Atomic spectroscopy;
- 1811;
- 2099;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- doi:10.3847/1538-4357/ac7eb9