Experimental tests of astrophysical photoionized plasma models using the Z-machine at Sandia National Laboratories*

The Z-machine at Sandia National Laboratories generates powerful X-ray radiation fluxes. This enables experiments to produce macroscopic plasmas at extreme conditions such as those found in accretion disk plasmas around black holes. Complex models for these non-Local-Thermodynamic-Equilibrium (non-LTE) plasmas remain mostly untested with laboratory data. We use a novel platform developed on the Z-machine to reach the same photon flux, density, and temperature conditions in black hole accretion disks. We will present model to data comparisons of the first ever high S/N iron L-shell x-ray emission spectra from a laboratory photoionized plasma. Such data have been a laboratory astrophysics goal for two decades but are even more critical now because of the “Super-Solar” iron abundance problem. Iron abundances inferred from x-ray spectra emitted by photoionized plasma around most black holes appear to contain 5-20 times more iron than the Sun. This contradicts the widely held expectation that most objects in the universe have the Sun’s composition. One prevailing theory is that effects of high electron density are not properly accounted for in the models. Reinterpreting the x-ray spectra with updated models resolved much of that discrepancy. However, a key question still remains: do photoionized plasma spectral models accurately account for x-ray emission? We will describe our progress in using this dataset to evaluate model accuracy and its potential to inform the super-solar iron abundance problem.