Kavli Affiliate: Claudio Ricci
| First 5 Authors: KristĂna Kallová, Peter G. Boorman, Claudio Ricci, ,
| Summary:
X-ray spectroscopy of heavily obscured Active Galactic Nuclei (AGN) offers a
unique opportunity to study the circum-nuclear environment of accreting
supermassive black holes (SMBHs). However, individual models describing the
obscurer have unique parameter spaces that give distinct parameter posterior
distributions when fit to the same data. To assess the impact of model-specific
parameter dependencies, we present a case study of the nearby heavily obscured
low-luminosity AGN NGC 3982, which has a variety of column density estimations
reported in the literature. We fit the same broadband XMM-Newton + NuSTAR
spectra of the source with five unique obscuration models and generate
posterior parameter distributions for each. By using global parameter
exploration, we traverse the full prior-defined parameter space to accurately
reproduce complex posterior shapes and inter-parameter degeneracies. The unique
model posteriors for the line-of-sight column density are broadly consistent,
predicting Compton-thick $N_{rm H}$ $>1.5times10^{24}rm cm^{-2}$ at the
3$sigma$ confidence level. The posterior median intrinsic X-ray luminosity in
the 2-10 keV band however was found to differ substantially, with values in the
range log $L_{ 2-10,{rm keV}}$ergs$^{-1}$ = 40.9-42.1 for the individual
models. We additionally show that the posterior distributions for each model
occupy unique regions of their respective multi-dimensional parameters spaces,
and how such differences can propagate into the inferred properties of the
central engine. We conclude by showcasing the improvement in parameter
inference attainable with the High Energy X-ray Probe (HEX-P) with a uniquely
broad simultaneous and high-sensitivity bandpass of 0.2-80 keV.
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