Radiation hydrodynamics simulations of the accretion-powered objects photoionized plasmas experiment on Z

Accreting black holes in X-ray binaries and active galactic nuclei constitute some of the most luminous objects in the universe. Model fits to reflection spectra from such systems have predicted unreasonably high Fe abundances, inconsistent with stellar evolutionary theory. This has revealed a need for increased scrutiny of the models. The Z machine at Sandia National Labs has a unique capability to probe the relevant physics. On the photoionized expanding foil platform, X-ray radiation from the Z-pinch is incident on a foil target, which reaches temperature, density, and photoionization conditions found in black hole accretion disks. It provides a means to benchmark astrophysical photoionized plasma codes (such as XSTAR) by measuring high resolution absorption and emission spectra, which can be used to test the underlying atomic physics in the models. We present initial results of simulations performed with the 1-D radiation hydrodynamics code HELIOS-CR to address questions of density and temperature gradients, evolving charge state distributions, and plasma expansion in the foil. Results from these simulations will help validate assumptions made in the spectroscopic analysis of data and facilitate more effective data-model comparisons.

This work is supported by Sandia National Laboratories, a multimission laboratory managed and operated by NTESS LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. DOE’s NNSA under contract DE-NA0003525.