The Nature of Soft Excess in ESO 362-G18 Revealed by XMM-Newton and NuSTAR Spectroscopy

2021

We present a detailed spectral analysis of the joint XMM-Newton and NuSTAR observations of the active galactic nuclei (AGN) in the Seyfert 1.5 Galaxy ESO 362-G18. The broadband ($0.3\mbox{--}79$ keV) spectrum shows the presence of a power-law continuum with a soft excess below $2$ keV, iron K$\alpha$ emission ($\sim 6.4$ keV), and a Compton hump (peaking at $\sim 20$ keV). We find that the soft excess can be modeled by two different possible scenarios: a warm ($kT_\mathrm{e}\sim0.2$ keV) and optically thick ($\tau\sim34$) Comptonizing corona; or with relativistically-blurred reflection off a high-density ($\log{[n_\mathrm{e}/\mathrm{cm}^{-3}]}>18.3$) inner disk. These two models cannot be e…