The Complex X-ray Obscuration Environment in the Radio Loud Type 2 Quasar 3C 223

TL;DR

This study investigates the complex, patchy X-ray obscuration environment in the radio loud Type 2 quasar 3C 223, revealing inhomogeneous gas distributions and physical processes affecting its spectrum, challenging previous assumptions about Compton-thick AGN.

Contribution

It provides the first detailed analysis of the inhomogeneous obscuring medium in a radio loud, Compton-thick candidate using broad-band X-ray spectra and models, highlighting physical complexities.

Findings

Obscuring gas is patchy with high and moderate column densities.

Additional physical processes influence the X-ray spectrum beyond standard models.

Three radio loud AGN are identified with global Compton-thick column densities.

Abstract

3C 223 is a radio loud, Type 2 quasar at $z=0.1365$ with an intriguing XMM-Newton spectrum that implicated it as a rare, Compton-thick ($N_{\rm H} \gtrsim 1.25 \times 10^{24}$ cm$^{-2}$) active galactic nucleus (AGN). We obtained contemporaneous XMM-Newton and NuSTAR spectra to fit the broad-band X-ray spectrum with the physically-motivated MYTorus and borus02 models. We confirm earlier results that the obscuring gas is patchy with both high (though not Compton-thick) levels of obscuration ($N_{\rm H} > 10^{23}$ cm$^{-2}$) and gas clouds with column densities up to an order of magnitude lower. The spectral fitting results indicate additional physical processes beyond those modeled in the spectral grids of MYTorus and borus02 impact the emergent spectrum: the Compton-scattering region may be extended beyond the putative torus; a ring of heavy Compton-thick material blocks most X-ray emission along the line of sight; or the radio jet is beamed, boosting the production of Fe K$\alpha$ line photons in the global medium compared with what is observed along the line of sight. We revisit a recent claim that no radio loud Compton-thick AGN have yet been conclusively shown to exist, finding three reported cases of radio loud AGN with global average (but not line-of-sight) column densities that are Compton-thick. Now that it is possible to separately determine line-of-sight and global column densities, inhomogeneity in the obscuring medium has consequences for how we interpet the spectrum and classify an AGN as "Compton-thick."